I have seen scores of expert developers getting perplexed with SQL Server in finding time only from datetime datatype. Let us have a quick glance look at the solution.

SQL Server 2000/2005

SELECT
CONVERT(VARCHAR(8),GETDATE(),108) AS HourMinuteSecond,
CONVERT(VARCHAR(8),GETDATE(),101) AS DateOnly
GO

SQL Server 2008

SELECT
CONVERT(TIME,GETDATE()) AS HourMinuteSecond,
CONVERT(DATE,GETDATE(),101) AS DateOnly
GO

I hope the above solution is clear to you all.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

I just received an email from one of my regular readers who is curious to know if there is any way to find out when a table is recently updated. I was ready with my answer! I promptly suggested him that if a table contains UpdatedDate or ModifiedDate date column with default together with value GETDATE(), he should make use of it. On close observation the table is not required to keep history when any row is inserted. However, the sole prerequisite is to be aware of when any table has been updated. That’s it!

If a user wants to finds out when was the last table updated he can query dynamic management view (dmv) – sys.dm_db_index_usage_stats and easily figure out when was the table updated last. Let us comprehend this example by creating a table and updating it. We can use dmv to determine when it was updated last.

USE AdventureWorks
GO
CREATE TABLE Test
(ID INT,
COL VARCHAR(100))
GO
INSERT INTO Test
SELECT 1,'First'
UNION ALL
SELECT 2,'Second'
GO

Now we have created a table and populated it with data. Next, we will run the following query to find out when it was last updated.

SELECT OBJECT_NAME(OBJECT_ID) AS DatabaseName, last_user_update,*
FROM sys.dm_db_index_usage_stats
WHERE database_id = DB_ID( 'AdventureWorks')
AND OBJECT_ID=OBJECT_ID('test')

Running query provides accurate details of when was  the table last updated. If WHERE condition is entirely removed it will provide details of the entire database.

Reference : Pinal Dave (http://blog.sqlauthority.com)

Today we will look at one very small but interesting feature of SQL Server. Please note that this is not much known feature of SQL Server. In SQL Server sometime there are requirement when T-SQL script has to wait for some time before executing next statement. It is quite common that developers depends on application to take over this delay issue. However, SQL Server itself has very strong time management function of WAITFOR. Let us see two usage of WAITFOR clause.

Official explanation of WAITFOR clause from Book Online is “Blocks the execution of a batch, stored procedure, or transaction until a specified time or time interval is reached, or a specified statement modifies or returns at least one row.”

Option 1 : Waitfor Delay in executing T-SQL
T-SQL runs after particular delay is completed.

SELECT GETDATE() CurrentTime
WAITFOR DELAY '00:00:05' ---- 5 Second Delay
SELECT GETDATE() CurrentTime

Option 2 : Waitfor Time in executing T-SQL
T-SQL runs after particular time has arrived.

DECLARE @MyDateTime DATETIME
/* Add 5 seconds to current time so
system waits for 5 seconds*/
SET @MyDateTime = DATEADD(s,5,GETDATE())
SELECT GETDATE() CurrentTime
WAITFOR TIME @MyDateTime
SELECT GETDATE() CurrentTime

Reference : Pinal Dave (http://blog.SQLAuthority.com)

A year ago I wrote post about SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice where I have discussed two different methods of getting datepart from datetime.

Method 1:
SELECT DATEADD(D, 0, DATEDIFF(D, 0, GETDATE()))

Method 2:
SELECT CONVERT(VARCHAR(10),GETDATE(),111)

I have summarized my post suggesting that either method works fine and I prefer to use Method 2. However, with additional tests and looking at SQL Server internals very carefully, I want to suggest that Method 1 is better in terms of performance. While running on GETDATE() both of the above functions are equally fast and efficient. However, when above query is ran on very large data table performance different is visible.

For testing purpose I have ran few queries where I am getting same result.

Run Following query 10 times with client statistics on ( Shift+Alter+S) in SSMS.

USE AdventureWorks
GO
SELECT DATEADD(d, 0, DATEDIFF(d, 0, StartDate))
FROM Production.WorkOrder
GO

Now run another query 10 times with client statistics on.

USE AdventureWorks
GO
SELECT CONVERT(VARCHAR(10),StartDate,111)
FROM Production.WorkOrder
GO

While looking at the average of statistics in it is clear that first query with DATEADD is much more efficient.

Let us compare both of the above script together and see the client statistics.

While comparing Numbers of Bytes sent across client and server as well client processing time, and total execution time in all case DATEADD is better. I suggest all my readers to use DATEADD when only DATEPART is required.

If you are using SQL Server 2008 it has new DATE datatype which does not have time part. I suggest to use DATE datatype or TIME datatype for users of SQL Server 2008. Read more SQL SERVER – 2008 – New DataTypes DATE and TIME.

If you want your date in any other format refer the UDF SQL SERVER – Get Date Time in Any Format – UDF – User Defined Functions.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Download SQL Server 2008 Interview Questions and Answers Complete List

Interview is very important event for any person. A good interview leads to good career if candidate is willing to learn. I always enjoy interview questions and answers series. This is my very humble attempt to write SQL Server 2008 interview questions and answers. SQL Server is very large subject and not everything is usually asked in interview. In interview what matters the most is conceptual knowledge and learning attitude.

I have listed all the series in this post so that it can be easily downloaded and used. All the questions are collected and listed in one PDF which is here to download. If you have any question or if you want to add to any of the question please send me mail or write a comment.

SQL SERVER – 2008 – Interview Questions and Answers – Part 1

SQL SERVER – 2008 – Interview Questions and Answers – Part 2

SQL SERVER – 2008 – Interview Questions and Answers – Part 3

SQL SERVER – 2008 – Interview Questions and Answers – Part 4

SQL SERVER – 2008 – Interview Questions and Answers – Part 5

SQL SERVER – 2008 – Interview Questions and Answers – Part 6

SQL SERVER – 2008 – Interview Questions and Answers – Part 7

SQL SERVER – 2008 – Interview Questions and Answers – Part 8

Download SQL Server 2008 Interview Questions and Answers Complete List

Reference : Pinal Dave (http://blog.SQLAuthority.com)

SQL SERVER – 2008 – Interview Questions and Answers Complete List Download

3) Questions of SQL SERVER 2008

What are the basic functions for master, msdb, model, tempdb and resource databases?

The master database holds information for all databases located on the SQL Server instance and is theglue that holds the engine together. Because SQL Server cannot start without a functioning masterdatabase, you must administer this database with care.

The msdb database stores information regarding database backups, SQL Agent information, DTS packages, SQL Server jobs, and some replication information such as for log shipping.

The tempdb holds temporary objects such as global and local temporary tables and stored procedures.

The model is essentially a template database used in the creation of any new user database created in the instance.

The resoure Database is a read-only database that contains all the system objects that are included with SQL Server. SQL Server system objects, such as sys.objects, are physically persisted in the Resource database, but they logically appear in the sys schema of every database. The Resource database does not contain user data or user metadata.

What is Service Broker?

Service Broker is a message-queuing technology in SQL Server that allows developers to integrate SQL Server fully into distributed applications. Service Broker is feature which provides facility to SQL Server to send an asynchronous, transactional message. it allows a database to send a message to another database without waiting for the response, so the application will continue to function if the remote database is temporarily unavailable. (Read More Here)

Where SQL server user names and passwords are stored in SQL server?

They get stored in System Catalog Views sys.server_principals and sys.sql_logins.

What is Policy Management?

Policy Management in SQL SERVER 2008 allows you to define and enforce policies for configuring and managing SQL Server across the enterprise. Policy-Based Management is configured in SQL Server Management Studio (SSMS).  Navigate to the Object Explorer and expand the Management node and the Policy Management node; you will see the Policies, Conditions, and Facets nodes. (Read More Here)

What is Replication and Database Mirroring?

Database mirroring can be used with replication to provide availability for the publication database. Database mirroring involves two copies of a single database that typically reside on different computers. At any given time, only one copy of the database is currently available to clients which are known as the principal database. Updates made by clients to the principal database are applied on the other copy of the database, known as the mirror database. Mirroring involves applying the transaction log from every insertion, update, or deletion made on the principal database onto the mirror database.

What are Sparse Columns?

A sparse column is another tool used to reduce the amount of physical storage used in a database. They are the ordinary columns that have an optimized storage for null values. Sparse columns reduce the space requirements for null values at the cost of more overhead to retrieve nonnull values. (Read More Here)

What does TOP Operator Do?

The TOP operator is used to specify the number of rows to be returned by a query. The TOP operator has new addition in SQL SERVER 2008 that it accepts variables as well as literal values and can be used with INSERT, UPDATE, and DELETES statements.

What is CTE?

CTE is an abbreviation Common Table Expression. A Common Table Expression (CTE) is an expression that can be thought of as a temporary result set which is defined within the execution of a single SQL statement. A CTE is similar to a derived table in that it is not stored as an object and lasts only for the duration of the query. (Read More Here)

What is MERGE Statement?
MERGE is a new feature that provides an efficient way to perform multiple DML operations. In previous versions of SQL Server, we had to write separate statements to INSERT, UPDATE, or DELETE data based on certain conditions, but now, using MERGE statement we can include the logic of such data modifications in one statement that even checks when the data is matched then just update it and when unmatched then insert it. One of the most important advantages of MERGE statement is all the data is read and processed only once.  (Read More Here)

What is Filtered Index?

Filtered Index is used to index a portion of rows in a table that means it applies filter on INDEX which improves query performance, reduce index maintenance costs, and reduce index storage costs compared with full-table indexes. When we see an Index created with some where clause then that is actually a FILTERED INDEX.

Which are new data types introduced in SQL SERVER 2008?

The GEOMETRY Type: The GEOMETRY data type is a system .NET common language runtime (CLR) data type in SQL Server. This type represents data in a two-dimensional Euclidean coordinate system.

The GEOGRAPHY Type: The GEOGRAPHY datatype’s functions are the same as with GEOMETRY. The difference between the two is that when you specify GEOGRAPHY, you are usually specifying points in terms of latitude and longitude.

New Date and Time Datatypes: SQL Server 2008 introduces four new datatypes related to date and time: DATE, TIME, DATETIMEOFFSET, and DATETIME2.

• DATE: The new DATE type just stores the date itself. It is based on the Gregorian calendar and handles years from 1 to 9999.
• TIME: The new TIME (n) type stores time with a range of 00:00:00.0000000 through 23:59:59.9999999. The precision is allowed with this type. TIME supports seconds down to 100 nanoseconds. The n in TIME (n) defines this level of fractional second precision, from 0 to 7 digits of precision.

• The DATETIMEOFFSET Type: DATETIMEOFFSET (n) is the time-zone-aware version of a datetime datatype. The name will appear less odd when you consider what it really is: a date + a time + a time-zone offset. The offset is based on how far behind or ahead you are from Coordinated Universal Time (UTC) time.

• The DATETIME2 Type: It is an extension of the datetime type in earlier versions of SQL Server. This new datatype has a date range covering dates from January 1 of year 1 through December 31 of year 9999. This is a definite improvement over the 1753 lower boundary of the datetime datatype. DATETIME2 not only includes the larger date range, but also has a timestamp and the same fractional precision that TIME type provides

What are the Advantages of using CTE?

• Using CTE improves the readability and makes maintenance of complex queries easy.
• The query can be divided into separate, simple, logical building blocks which can be then used to build more complex CTEs until final result set is generated.
• CTE can be defined in functions, stored procedures, triggers or even views.
• After a CTE is defined, it can be used as a Table or a View and can SELECT, INSERT, UPDATE or DELETE Data.

© Copyright 2000-2009 Pinal Dave. All Rights Reserved. SQLAuthority.com

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Recently I have recieved email from Vivek Jamwal, which contains many useful SQL Server Date functions.

----Today
SELECT GETDATE() 'Today'
----Yesterday
SELECT DATEADD(d,-1,GETDATE()) 'Yesterday'
----First Day of Current Week
SELECT DATEADD(wk,DATEDIFF(wk,0,GETDATE()),0) 'First Day of Current Week'
----Last Day of Current Week
SELECT DATEADD(wk,DATEDIFF(wk,0,GETDATE()),6) 'Last Day of Current Week'
----First Day of Last Week
SELECT DATEADD(wk,DATEDIFF(wk,7,GETDATE()),0) 'First Day of Last Week'
----Last Day of Last Week
SELECT DATEADD(wk,DATEDIFF(wk,7,GETDATE()),6) 'Last Day of Last Week'
----First Day of Current Month
SELECT DATEADD(mm,DATEDIFF(mm,0,GETDATE()),0) 'First Day of Current Month'
----Last Day of Current Month
SELECT DATEADD(ms,- 3,DATEADD(mm,0,DATEADD(mm,DATEDIFF(mm,0,GETDATE())+1,0))) 'Last Day of Current Month'
----First Day of Last Month
SELECT DATEADD(mm,-1,DATEADD(mm,DATEDIFF(mm,0,GETDATE()),0)) 'First Day of Last Month'
----Last Day of Last Month
SELECT DATEADD(ms,-3,DATEADD(mm,0,DATEADD(mm,DATEDIFF(mm,0,GETDATE()),0))) 'Last Day of Last Month'
----First Day of Current Year
SELECT DATEADD(yy,DATEDIFF(yy,0,GETDATE()),0) 'First Day of Current Year'
----Last Day of Current Year
SELECT DATEADD(ms,-3,DATEADD(yy,0,DATEADD(yy,DATEDIFF(yy,0,GETDATE())+1,0))) 'Last Day of Current Year'
----First Day of Last Year
SELECT DATEADD(yy,-1,DATEADD(yy,DATEDIFF(yy,0,GETDATE()),0)) 'First Day of Last Year'
----Last Day of Last Year
SELECT DATEADD(ms,-3,DATEADD(yy,0,DATEADD(yy,DATEDIFF(yy,0,GETDATE()),0))) 'Last Day of Last Year'

ResultSet:

Today
———————–
2008-08-29 21:54:58.967

Yesterday
———————–
2008-08-28 21:54:58.967

First Day of Current Week
————————-
2008-08-25 00:00:00.000

Last Day of Current Week
————————
2008-08-31 00:00:00.000

First Day of Last Week
———————–
2008-08-18 00:00:00.000

Last Day of Last Week
———————–
2008-08-24 00:00:00.000

First Day of Current Month
————————–
2008-08-01 00:00:00.000

Last Day of Current Month
————————-
2008-08-31 23:59:59.997

First Day of Last Month
———————–
2008-07-01 00:00:00.000

Last Day of Last Month
———————–
2008-07-31 23:59:59.997

First Day of Current Year
————————-
2008-01-01 00:00:00.000

Last Day of Current Year
————————
2008-12-31 23:59:59.997

First Day of Last Year
———————–
2007-01-01 00:00:00.000

Last Day of Last Year
———————–
2007-12-31 23:59:59.997

Reference : Pinal Dave (http://blog.SQLAuthority.com), Vivek Jamwal

One of the reader Nanda of SQLAuthority.com has posted very detailed script of converting any date time in desired format. I suggest every reader of this blog to save this script in your permanent code bookmark and use it when you need it.

Refer the function and get familiar yourself with different format this function support. I have added few examples of how this function can be used at the end of the article. You can download whole code in ZIP format as well.

Download Get Date Time in Any Format Script (ZIP)

CREATE FUNCTION [dbo].[ufsFormat]
(
@Date datetime,
@fORMAT VARCHAR(80)
)
RETURNS NVARCHAR(80)
AS
BEGIN
DECLARE @Dateformat INT
DECLARE @ReturnedDate VARCHAR(80)
DECLARE @TwelveHourClock INT
DECLARE @Before INT
DECLARE @pos INT
DECLARE @Escape INT
-- (c) Pinal Dave http://www.SQLAuthority.com
SELECT @ReturnedDate='error! unrecognised format '+@format
SELECT @DateFormat=CASE @format
WHEN 'mmm dd yyyy hh:mm AM/PM' THEN 100
WHEN 'mm/dd/yy' THEN 1
WHEN 'mm/dd/yyyy' THEN 101
WHEN 'yy.mm.dd' THEN 2
WHEN 'dd/mm/yy' THEN 3
WHEN 'dd.mm.yy' THEN 4
WHEN 'dd-mm-yy' THEN 5
WHEN 'dd Mmm yy' THEN 6
WHEN 'Mmm dd, yy' THEN 7
WHEN 'hh:mm:ss' THEN 8
WHEN 'yyyy.mm.dd' THEN 102
WHEN 'dd/mm/yyyy' THEN 103
WHEN 'dd.mm.yyyy' THEN 104
WHEN 'dd-mm-yyyy' THEN 105
WHEN 'dd Mmm yyyy' THEN 106
WHEN 'Mmm dd, yyyy' THEN 107
WHEN 'Mmm dd yyyy hh:mm:ss:ms AM/PM' THEN 9
WHEN 'Mmm dd yyyy hh:mi:ss:mmm AM/PM' THEN 9
WHEN 'Mmm dd yy hh:mm:ss:ms AM/PM' THEN 109
WHEN 'mm-dd-yy' THEN 10
WHEN 'mm-dd-yyyy' THEN 110
WHEN 'yy/mm/dd' THEN 11
WHEN 'yyyy/mm/dd' THEN 111
WHEN 'yymmdd' THEN 12
WHEN 'yyyymmdd' THEN 112
WHEN 'dd Mmm yyyy hh:mm:ss:Ms' THEN 113
WHEN 'hh:mm:ss:Ms' THEN 14
WHEN 'yyyy-mm-dd hh:mm:ss' THEN 120
WHEN 'yyyy-mm-dd hh:mm:ss.Ms' THEN 121
WHEN 'yyyy-mm-ddThh:mm:ss.Ms' THEN 126
WHEN 'dd Mmm yyyy hh:mm:ss:ms AM/PM' THEN 130
WHEN 'dd/mm/yy hh:mm:ss:ms AM/PM' THEN 131
WHEN 'RFC822' THEN 2
WHEN 'dd Mmm yyyy hh:mm' THEN 4
ELSE 1 END
SELECT @ReturnedDate='error! unrecognised format ' +@format+CONVERT(VARCHAR(10),@DateFormat)
IF @DateFormat>=0
SELECT @ReturnedDate=CONVERT(VARCHAR(80),@Date,@DateFormat)
--check for favourite and custom formats that can be done quickly
ELSE IF @DateFormat=-2--then it is RFC822 format
SELECT @ReturnedDate=LEFT(DATENAME(dw, @Date),3) + ', ' + STUFF(CONVERT(NVARCHAR,@Date,113),21,4,' GMT')
ELSE IF @DateFormat=-4--then it is european day format with minutes
SELECT @ReturnedDate=CONVERT(CHAR(17),@Date,113)
ELSE
BEGIN
SELECT @Before=LEN(@format)
SELECT @Format=REPLACE(REPLACE(REPLACE( @Format,'AM/PM','#'),'AM','#'),'PM','#')
SELECT @TwelveHourClock=CASE WHEN @Before >LEN(@format) THEN 109 ELSE 113 END, @ReturnedDate=''
WHILE (1=1)--forever
BEGIN
SELECT @pos=PATINDEX('%[yqmidwhs:#]%',@format+' ')
IF @pos=0--no more date format strings
BEGIN
SELECT @ReturnedDate=@ReturnedDate+@format
BREAK
END
IF @pos>1--some stuff to pass through first
BEGIN
SELECT @escape=CHARINDEX ('\',@Format+'\') --is it a literal character that is escaped?
IF @escape<@pos BEGIN
SET @ReturnedDate=@ReturnedDate+SUBSTRING(@Format,1,@escape-1) +SUBSTRING(@format,@escape+1,1)
SET @format=RTRIM(SUBSTRING(@Format,@Escape+2,80))
CONTINUE
END
SET @ReturnedDate=@ReturnedDate+SUBSTRING(@Format,1,@pos-1)
SET @format=RTRIM(SUBSTRING(@Format,@pos,80))
END
SELECT @pos=PATINDEX('%[^yqmidwhs:#]%',@format+' ')--get the end
SELECT @ReturnedDate=@ReturnedDate+--'('+substring(@Format,1,@pos-1)+')'+
CASE SUBSTRING(@Format,1,@pos-1)
--Mmmths as 1--12
WHEN 'M' THEN CONVERT(VARCHAR(2),DATEPART(MONTH,@Date))
--Mmmths as 01--12
WHEN 'Mm' THEN CONVERT(CHAR(2),@Date,101)
--Mmmths as Jan--Dec
WHEN 'Mmm' THEN CONVERT(CHAR(3),DATENAME(MONTH,@Date))
--Mmmths as January--December
WHEN 'Mmmm' THEN DATENAME(MONTH,@Date)
--Mmmths as the first letter of the Mmmth
WHEN 'Mmmmm' THEN CONVERT(CHAR(1),DATENAME(MONTH,@Date))
--Days as 1--31
WHEN 'D' THEN CONVERT(VARCHAR(2),DATEPART(DAY,@Date))
--Days as 01--31
WHEN 'Dd' THEN CONVERT(CHAR(2),@date,103)
--Days as Sun--Sat
WHEN 'Ddd' THEN CONVERT(CHAR(3),DATENAME(weekday,@Date))
--Days as Sunday--Saturday
WHEN 'Dddd' THEN DATENAME(weekday,@Date)
--Years as 00--99
WHEN 'Yy' THEN CONVERT(CHAR(2),@Date,12)
--Years as 1900--9999
WHEN 'Yyyy' THEN DATENAME(YEAR,@Date)
WHEN 'hh:mm:ss' THEN SUBSTRING(CONVERT(CHAR(30),@date,@TwelveHourClock),13,8)
WHEN 'hh:mm:ss:ms' THEN SUBSTRING(CONVERT(CHAR(30),@date,@TwelveHourClock),13,12)
WHEN 'h:mm:ss' THEN SUBSTRING(CONVERT(CHAR(30),@date,@TwelveHourClock),13,8)
--tthe SQL Server BOL syntax, for compatibility
WHEN 'hh:mi:ss:mmm' THEN SUBSTRING(CONVERT(CHAR(30),@date,@TwelveHourClock),13,12)
WHEN 'h:mm:ss:ms' THEN SUBSTRING(CONVERT(CHAR(30),@date,@TwelveHourClock),13,12)
WHEN 'H:m:s' THEN SUBSTRING(REPLACE(':'+SUBSTRING(CONVERT(CHAR(30), @Date,@TwelveHourClock),13,8),':0',':'),2,30)
WHEN 'H:m:s:ms' THEN SUBSTRING(REPLACE(':'+SUBSTRING(CONVERT(CHAR(30), @Date,@TwelveHourClock),13,12),':0',':'),2,30)
--Hours as 00--23
WHEN 'hh' THEN REPLACE(SUBSTRING(CONVERT(CHAR(30), @Date,@TwelveHourClock),13,2),' ','0')
--Hours as 0--23
WHEN 'h' THEN LTRIM(SUBSTRING(CONVERT(CHAR(30), @Date,@TwelveHourClock),13,2))
--Minutes as 00--59
WHEN 'Mi' THEN DATENAME(minute,@date)
WHEN 'mm' THEN DATENAME(minute,@date)
WHEN 'm' THEN CONVERT(VARCHAR(2),DATEPART(minute,@date))
--Seconds as 0--59
WHEN 'ss' THEN DATENAME(second,@date)
--Seconds as 0--59
WHEN 'S' THEN CONVERT(VARCHAR(2),DATEPART(second,@date))
--AM/PM
WHEN 'ms' THEN DATENAME(millisecond,@date)
WHEN 'mmm' THEN DATENAME(millisecond,@date)
WHEN 'dy' THEN DATENAME(dy,@date)
WHEN 'qq' THEN DATENAME(qq,@date)
WHEN 'ww' THEN DATENAME(ww,@date)
WHEN '#' THEN REVERSE(SUBSTRING(REVERSE(CONVERT(CHAR(26), @date,109)),1,2))
ELSE
SUBSTRING(@Format,1,@pos-1)
END
SET @format=RTRIM(SUBSTRING(@Format,@pos,80))
END
END
RETURN @ReturnedDate
END
GO
SELECT [dbo].[ufsFormat] ('8/7/2008', 'mm/dd/yy')
GO
SELECT [dbo].[ufsFormat] ('8/7/2008', 'hh:mm:ss')
GO
SELECT [dbo].[ufsFormat] ('8/7/2008', 'mmm')
GO
SELECT [dbo].[ufsFormat] ('8/7/2008', 'Mmm dd yyyy hh:mm:ss:ms AM/PM')
GO
SELECT [dbo].[ufsFormat] ('8/7/2008', '#')
GO


Reference : Pinal Dave (http://blog.SQLAuthority.com) , Nanda

How to get current system date time in SQL Server?

First thing which comes to many users is using following script.

SELECT GETDATE() AS CurrentDateTime

Above method is not the only method to retrieve the current system date time for SQL Server. SQL Server 2008 has many different function which provides current system date time in different format and little difference in details.

SELECT 'SYSDATETIME' AS FunctionName, SYSDATETIME() AS DateTimeFormat
UNION ALL
SELECT 'SYSDATETIMEOFFSET', SYSDATETIMEOFFSET()
UNION ALL
SELECT 'SYSUTCDATETIME', SYSUTCDATETIME()
UNION ALL
SELECT 'CURRENT_TIMESTAMP', CURRENT_TIMESTAMP
UNION ALL
SELECT 'GETDATE', GETDATE()
UNION ALL
SELECT 'GETUTCDATE', GETUTCDATE()

In SQL Server 2008, use any of the above function depending on your need.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

If you want to find current datetime in SQL Server I suggest to read the following post :

SQL SERVER – Retrieve Current Date Time in SQL Server CURRENT_TIMESTAMP, GETDATE(), {fn NOW()}

This post is related to new feature available in SQL Server 2008. In SQL Server 2008 there is a function which provides current offset of the system from GMT time as well. Basically it shows the system datetime with offset. I think this can be useful in some of the instances where SQL Server are depending on the time offset.

SELECT SYSDATETIMEOFFSET() AS 'Windows System Time'
GO

Reference : Pinal Dave (http://blog.SQLAuthority.com)

I have been playing with SQL Server 2008 recently. There are many new features which SQL Server 2008 have. One of the interesting addition to SQL Server 2008 is system table field which records when SQL Server was started. This field has data type as datetime that is why it is precise to 3 milisecond.

Note : This will not work with SQL Server 2005 or earlier version. This works with SQL Server 2008 only.

SELECT sqlserver_start_time
FROM sys.dm_os_sys_info

ResultSet:
sqlserver_start_time
———————–
2008-06-27 20:51:53.317

Reference : Pinal Dave (http://blog.SQLAuthority.com)

I have been asked many times when there is DATENAME function available why do I go in exercise of writing UDF For the getting the day of the week. Answer is : I just like it!

SELECT DATENAME(dw, GETDATE())

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Datetime functions and stored procedures always interests me. Nanda Kumar has suggested modification to previous written article about SQL SERVER – SQL SERVER – UDF – Get the Day of the Week Function – Part 2. He has improved on UDF.

CREATE FUNCTION dbo.udf_DayOfWeek(@dtDate DATETIME)
RETURNS VARCHAR(10)
AS
BEGIN
DECLARE @rtDayofWeek VARCHAR(10)
DECLARE @weekDay INT
----Here I have subtracted 7 For keeping Sunday as the First day like wise for Monday we need to subtract 2 and so on
SET @weekDay=((DATEPART(dw,@dtDate)+@@DATEFIRST-7)%7)
SELECT @rtDayofWeek = CASE @weekDay
WHEN 1 THEN 'Sunday'
WHEN 2 THEN 'Monday'
WHEN 3 THEN 'Tuesday'
WHEN 4 THEN 'Wednesday'
WHEN 5 THEN 'Thursday'
WHEN 6 THEN 'Friday'
WHEN 0 THEN 'Saturday'
END
RETURN (@rtDayofWeek)
END
GO
SELECT dbo.udf_dayofweek(GETDATE())

Reference : Pinal Dave (http://blog.SQLAuthority.com) , Nanda Kumar

I have written article about SQL SERVER – UDF – Get the Day of the Week Function. I have received good modified script from reader Mihir Popat has suggested another code where Sunday does not have to be necessary the first day of the week.

CREATE FUNCTION dbo.udf_DayOfWeek(@dtDate DATETIME)
RETURNS VARCHAR(10)
AS
BEGIN
DECLARE @rtDayofWeek VARCHAR(10)
DECLARE @weekDay INT
-- Here I have subtracted 7 For keeping Sunday as the First day
-- like wise for Monday we need to subtract 2 and so on
SET @weekDay = ((DATEPART(dw,GETDATE())+@@DATEFIRST-7)%7)
SELECT @rtDayofWeek = CASE @weekDay
WHEN 1 THEN 'Sunday'
WHEN 2 THEN 'Monday'
WHEN 3 THEN 'Tuesday'
WHEN 4 THEN 'Wednesday'
WHEN 5 THEN 'Thursday'
WHEN 6 THEN 'Friday'
WHEN 7 THEN 'Saturday'
END
RETURN (@rtDayofWeek)
END
GO
SELECT dbo.udf_DayOfWeek(GETDATE())

Reference : Pinal Dave (http://blog.SQLAuthority.com), Mihir Popat

It gives me great pleasure to write articles like today’s one because I have received great comment from one of regular reader who has taken UDF written by me and created another UDF using that UDF which enhances functionality of it. I had written previous article about SQL SERVER – UDF – Function to Display Current Week Date and Day – Weekly Calendar. Reader of this blog and great SQL expert Dan Golden has wrote another UDF which uses UDF written by me. I thank Dan Golden for his contribution to this blog. I have modified his function a bit to remove error when it was missing displaying first or last week in few cases, however I will give full credit to him for his thought.

I also encourage my other readers to submit their articles to me, if I think your article will benefit other readers I will publish it here with your name. Do not send me article if it is not written by you.

Step 1 : Create UDF to display current week date and day – Weekly Calender.
USE AdventureWorks;
GO
CREATE FUNCTION dbo.DisplayCurrentWeekDays
(@today SMALLDATETIME)
RETURNS @WeekDateDay TABLE
(
Sunday SMALLDATETIME,
Monday SMALLDATETIME,
Tuesday SMALLDATETIME,
Wednesday SMALLDATETIME,
Thursday SMALLDATETIME,
Friday SMALLDATETIME,
Saturday SMALLDATETIME
)
AS
/*
Purpose: To return the weekly calendar for the week any date
By: Pinal Dave -- SQLAuthority.com
On: 6/8/2007
*/
BEGIN
DECLARE @day INT
SET @today = CAST(CONVERT(VARCHAR(10), @today, 101) AS SMALLDATETIME)
SET @day = DATEPART(dw, @today)
INSERT INTO @WeekDateDay (Sunday, Monday,
Tuesday, Wednesday, Thursday, Friday, Saturday)
SELECT DATEADD(dd, 1 - @day, @today) Sunday,
DATEADD(dd, 2 - @day, @today) Monday,
DATEADD(dd, 3 - @day, @today) Tuesday,
DATEADD(dd, 4 - @day, @today) Wednesday,
DATEADD(dd, 5 - @day, @today) Thursday,
DATEADD(dd, 6 - @day, @today) Friday,
DATEADD(dd, 7 - @day, @today) Saturday
RETURN
END
GO

Step 2 : Create UDF to display current month date and day – Monthly Calender
USE AdventureWorks;
GO
CREATE FUNCTION dbo.GetSQLcalendar(@WhatDate SMALLDATETIME)
RETURNS @WeekDateDay TABLE
(
Sunday SMALLDATETIME,
Monday SMALLDATETIME,
Tuesday SMALLDATETIME,
Wednesday SMALLDATETIME,
Thursday SMALLDATETIME,
Friday SMALLDATETIME,
Saturday SMALLDATETIME
)
AS
BEGIN
/*
Purpose: To return a calendar fOR whatever MONTH you want,
driven by the date you pick AS a variable.
By: Dan Golden
On: 2/20/2008
*/
DECLARE @FourWeeksAgo SMALLDATETIME
SET @FourWeeksAgo = DATEADD(d,-28,@WhatDate)
DECLARE @ThreeWeeksAgo SMALLDATETIME
SET @ThreeWeeksAgo = DATEADD(d,-21,@WhatDate)
DECLARE @TwoWeeksAgo SMALLDATETIME
SET @TwoWeeksAgo = DATEADD(d,-14,@WhatDate)
DECLARE @PreviousWeek SMALLDATETIME
SET @PreviousWeek = DATEADD(d,-7,@WhatDate)
DECLARE @ThisWeek SMALLDATETIME
SET @ThisWeek = (@WhatDate)
DECLARE @NextWeek SMALLDATETIME
SET @NextWeek = DATEADD(d,7,@WhatDate)
DECLARE @LastWeek SMALLDATETIME
SET @LastWeek = DATEADD(d,14,@WhatDate)
DECLARE @AfterLastWeek SMALLDATETIME
SET @AfterLastWeek = DATEADD(d,21,@WhatDate)
DECLARE @TwoAfterLastWeek SMALLDATETIME
SET @TwoAfterLastWeek = DATEADD(d,28,@WhatDate)
INSERT INTO @WeekDateDay (Sunday, Monday, Tuesday,
Wednesday, Thursday, Friday, Saturday)
SELECT *
FROM
(
SELECT CASE MONTH(calendar.Sunday)
WHEN MONTH(@WhatDate)
THEN calendar.Sunday
ELSE NULL END AS 'Sunday',
CASE MONTH(calendar.Monday)
WHEN MONTH(@WhatDate)
THEN calendar.Monday
ELSE NULL END AS 'Monday',
CASE MONTH(calendar.Tuesday)
WHEN MONTH(@WhatDate)
THEN calendar.Tuesday
ELSE NULL END AS 'Tuesday',
CASE MONTH(calendar.Wednesday)
WHEN MONTH(@WhatDate)
THEN calendar.Wednesday
ELSE NULL END AS 'Wednesday',
CASE MONTH(calendar.Thursday)
WHEN MONTH(@WhatDate)
THEN calendar.Thursday
ELSE NULL END AS 'Thursday',
CASE MONTH(calendar.Friday)
WHEN MONTH(@WhatDate)
THEN calendar.Friday
ELSE NULL END AS 'Friday',
CASE MONTH(calendar.Saturday)
WHEN MONTH(@WhatDate)
THEN calendar.Saturday
ELSE NULL END AS 'Saturday'
FROM
(
SELECT *
FROM dbo.DisplayCurrentWeekDays(@FourWeeksAgo)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@ThreeWeeksAgo)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@TwoWeeksAgo)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@PreviousWeek)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@ThisWeek)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@NextWeek)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@LastWeek)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@AfterLastWeek)
UNION ALL
SELECT *
FROM dbo.DisplayCurrentWeekDays(@TwoAfterLastWeek)
) calendar
) dates
WHERE dates.sunday IS NOT NULL
OR dates.monday IS NOT NULL
OR dates.tuesday IS NOT NULL
OR dates.wednesday IS NOT NULL
OR dates.thursday IS NOT NULL
OR dates.friday IS NOT NULL
OR dates.saturday IS NOT NULL
RETURN
END
GO

Step 3 : Use recently created UDF to get the current month ’s calender. You can pass any date to this calender and it will return that month and years calender.
USE AdventureWorks;
GO
DECLARE @WhatDay SMALLDATETIME
SELECT @WhatDay = GETDATE(); -- you can also put here any date like 07/01/1990
SELECT ISNULL(CONVERT(NVARCHAR(20), Sunday, 101), '') AS 'Sunday',
ISNULL(CONVERT(NVARCHAR(20), Monday, 101), '') AS 'Monday',
ISNULL(CONVERT(NVARCHAR(20), Tuesday, 101), '') AS 'Tuesday',
ISNULL(CONVERT(NVARCHAR(20), Wednesday, 101), '') AS 'Wednesday',
ISNULL(CONVERT(NVARCHAR(20), Thursday, 101), '') AS 'Thursday',
ISNULL(CONVERT(NVARCHAR(20), Friday, 101), '') AS 'Friday',
ISNULL(CONVERT(NVARCHAR(20), Saturday, 101), '') AS 'Saturday'
FROM dbo.GetSQLcalendar(@WhatDay)
GO

Above query will return you monthly calender for date passed to function.

Reference : Pinal Dave (http://blog.SQLAuthority.com) , Dan Golden

Following question was asking by one of long time reader who really liked trick of SQL SERVER – Explanation SQL Command GO and SQL SERVER – Insert Multiple Records Using One Insert Statement – Use of UNION ALL. She asked how can I execute same code multiple times without Copy and Paste multiple times in Query Editor. The answer to this question is very simple. Use the command GO. Following example demonstrate how GO can be used to execute same code multiple times.
SELECT GETDATE() AS CurrentTime
GO 5
Above code will return current time 5 times as GO is followed with five times. The result is displayed with “Result to Text” mode on.
Beginning execution loop
CurrentTime
———————–
2008-01-19 1:52:54.200

(1 row(s) affected)

CurrentTime
———————–
2008-01-19 11:52:54.217

(1 row(s) affected)

CurrentTime
———————–
2008-01-19 11:52:54.217

(1 row(s) affected)

CurrentTime
———————–
2008-01-19 11:52:54.217

(1 row(s) affected)

CurrentTime
———————–
2008-01-19 11:52:54.233

(1 row(s) affected)
Batch execution completed 5 times.

Reference : Pinal Dave (http://blog.SQLAuthority.com)

One of our project manager asked me why SQL Server does not have only DATE or TIME datatypes? I thought his question is very valid, he is not DBA however he understands the RDBMS concepts very well. I find his question very interesting. I told him that there are ways to do that in SQL Server 2005 and earlier versions. He asked me but if there are DATE and TIME datatypes not DATETIME combined.

This question we all DBA had for many years and we all wanted DATE and TIME separate datatypes then DATETIME combined. Microsoft has incorporated this feature in SQL Server 2008. It supports many new DATETIME datatypes. Today we will see DATE and TIME specifically.

DATE datatype Explanation

SQL SERVER 2005:
DECLARE @Date AS DATETIME
SET @Date = GETDATE()
SELECT @Date OriginalDate, CONVERT(VARCHAR(10),@Date,111) CastDate

ResultSet:
OriginalDate CastDate
———————– ———-
2007-12-22 17:48:14.640 2007/12/22

SQL SERVER 2008:
DECLARE @Date AS DATE
SET @Date = GETDATE()
SELECT @Date OriginalDate

ResultSet:
OriginalDate
———————–
2007-12-22

TIME datatype Explanation

SQL SERVER 2005:
DECLARE @Time AS DATETIME
SET @Time = GETDATE()
SELECT @Time OriginalTime, CONVERT(VARCHAR(10),@Time,108) CastTime

ResultSet:
OriginalTime CastTime
———————– ———-
2007-12-22 17:48:57.200 17:48:57

SQL SERVER 2008:
DECLARE @Time AS TIME
SET @Time = GETDATE()
SELECT @Time OriginalTime

ResultSet:
OriginalTime
———————–
17:48:57.2000000

Reference : Pinal Dave (http://blog.SQLAuthority.com)

SQL SERVER – Cursor to Kill All Process in Database

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SQL SERVER – Difference between DISTINCT and GROUP BY – Distinct vs Group By

SQL SERVER – Index Seek Vs. Index Scan (Table Scan)

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SQL SERVER – Six Properties of Relational Tables

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SQL SERVER – Good, Better and Best Programming Techniques

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SQL SERVER – 2005 TOP Improvements/Enhancements

SQL SERVER – 2005/2000 Examples and Explanation for GOTO

SQL SERVER – Explanation SQL Commando GO

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SQL SERVER – Disable Index – Enable Index – ALTER Index

SQL SERVER – 2005 – SSMS Change T-SQL Batch Separator

SQL SERVER – SQL Code Formatter Tools

SQL SERVER – 2005 Comparison EXCEPT operator vs. NOT IN

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SQL SERVER – 2005 Constraint on VARCHAR(MAX) Field To Limit It Certain Length

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SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice

SQL SERVER – 2005 T-SQL Paging Query Technique Comparison (OVER and ROW_NUMBER()) – CTE vs. Derived Table

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SQL SERVER – Explanation and Comparison of NULLIF and ISNULL

SQL SERVER – 2005 Row Overflow Data Explanation

SQL SERVER – Comparison Index Fragmentation, Index De-Fragmentation, Index Rebuild – SQL SERVER 2000 and SQL SERVER 2005

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SQL SERVER – 2005 Best Practices Analyzer Tutorial – Sample Example

SQL SERVER – 2005 – List All Stored Procedure Modified in Last N Days

SQL SERVER – Count Duplicate Records – Rows

SQL SERVER – CASE Statement in ORDER BY Clause – ORDER BY using Variable

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SQL SERVER – UDF – Validate Integer Function

SQL SERVER – What is SQL? How to pronounce SQL?

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SQL SERVER – 2005 – Explanation and Script for Online Index Operations – Create, Rebuild, Drop

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SQL SERVER – T-SQL Script to Insert Carriage Return and New Line Feed in Code

SQL SERVER – 2005 – T-SQL Script to Attach and Detach Database

SQL SERVER – Actual Execution Plan vs. Estimated Execution Plan

SQL SERVER – 2005 – Search Stored Procedure Code – Search Stored Procedure Text

SQL SERVER – 2005 – Find Tables With Foreign Key Constraint in Database

SQL SERVER – 2005 – Find Tables With Primary Key Constraint in Database

SQL SERVER – 2005 – Introduction and Explanation to sqlcmd

SQL SERVER – UDF – User Defined Function – Get Number of Days in Month

SQL SERVER – 2005 – Start Stop Restart SQL Server From Command Prompt

SQL SERVER – 2005 – List All The Constraint of Database – Find Primary Key and Foreign Key Constraint in Database

SQL SERVER – UDF – Validate Positive Integer Function – Validate Natural Integer Function

SQL SERVER – Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT

SQL SERVER – 2005 – OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE

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Reference : Pinal Dave (http://blog.SQLAuthority.com)

While doing surprise code review of Jr. DBA I found interesting syntax DATEFORMAT. This keywords is very less used as CONVERT and CAST can do much more than this command. It is still interesting to learn about learn about this new syntax.

Sets the order of the dateparts (month/day/year) for entering datetime or smalldatetime data. This command allows you to input strings that would normally not be recognized by SQL server as dates. The SET DATEFORMAT command lets you specify order of data parts. The options for DATEFORMAT are mdy, dmy, ymd, ydm, myd, or dym. The default DATEFORMAT is mdy. This commands allows to INSERT/UPDATE dates with different formats without doing any special data conversions.The setting of SET DATEFORMAT is set at execute or run time and not at parse time. Following example demonstrate how character string can be converted to proper dateformat using SET DATEFORMAT command.

Example:
CREATE TABLE #tempTable (DateFormatSample SMALLDATETIME)
SET DATEFORMAT MDY
INSERT INTO #tempTable
VALUES ('09/28/2007')
SET DATEFORMAT YDM
INSERT INTO #tempTable
VALUES ('2007/28/09')
SET DATEFORMAT YMD
INSERT INTO #tempTable
VALUES ('2007/08/28')
SELECT DateFormatSample
FROM #tempTable
DROP TABLE #tempTable
Resultset:
DateFormatSample
———————–
2007-09-28 00:00:00
2007-09-28 00:00:00
2007-08-28 00:00:00

Reference : Pinal Dave (http://blog.SQLAuthority.com)

Following User Defined Function (UDF) returns the numbers of days in month. It is very simple yet very powerful and full proof UDF.
CREATE FUNCTION [dbo].[udf_GetNumDaysInMonth] ( @myDateTime DATETIME )
RETURNS INT
AS
BEGIN
DECLARE @rtDate INT
SET @rtDate = CASE WHEN MONTH(@myDateTime)
IN (1, 3, 5, 7, 8, 10, 12) THEN 31
WHEN MONTH(@myDateTime) IN (4, 6, 9, 11) THEN 30
ELSE CASE WHEN (YEAR(@myDateTime) % 4 = 0
AND
YEAR(@myDateTime) % 100 != 0)
OR
(YEAR(@myDateTime) % 400 = 0)
THEN 29
ELSE 28 END
END
RETURN @rtDate
END
GO

Run following script in Query Editor:
SELECT dbo.udf_GetNumDaysInMonth(GETDATE()) NumDaysInMonth
GO

ResultSet:
NumDaysInMonth
———————–
31

Reference : Pinal Dave (http://blog.SQLAuthority.com)