Comments on: SQL SERVER – Primary Key Constraints and Unique Key Constraints

By: Suma

Suma — Wed, 08 May 2013 13:29:54 +0000

Hi ,

Why unique key allows only NULL value when one NULL is different from other NULL.

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By: SQL SERVER – Primary Key and NonClustered Index in Simple Words « SQL Server Journey with SQL Authority

Sun, 10 Feb 2013 01:30:32 +0000

[...] I have been writing a weekly round up from my blog where I go over last six years of blog posts and pick the best posts from the pasts. While I do this, there are two major place where I focus 1) If there are change in features – I re-blog about it with additional details or 2) If I have not provided complete information six years ago, I try to fill up the gap now. Well, just like everything my knowledge and writing skills have evolved. Before continuing please read my latest memory lane blog post where in 2007 I wrote scripts for Primary Key and Unique Key. [...]

By: SQL SERVER – Weekly Series – Memory Lane – #015 « SQL Server Journey with SQL Authority

Sat, 09 Feb 2013 01:30:22 +0000

[...] Primary Key Constraints and Unique Key Constraints There is a big difference between Primary Key and Unique Key, however, quite common they are confused and mixed up. Well, this blog post explains the concept in very simple words and explains the scripts as well. [...]

By: Raghvendra Pratap Singh

Raghvendra Pratap Singh — Fri, 11 Jan 2013 08:05:35 +0000

–we can disable primary key index like this
alter index ix_empId on employee disable;

By: Sunder

Sunder — Wed, 02 Jan 2013 07:53:11 +0000

Dear Pinal Sir,

Please explain me how to disable Primary key constraint?

By: suhail

suhail — Tue, 18 Dec 2012 05:48:29 +0000

I learnt lot from this conversation…………

By: saranyait1991

saranyait1991 — Thu, 29 Nov 2012 09:26:00 +0000

I want to throw exception while entering the values in registration form n ve to store it in database… wen i am giving email id n second time also i am using same id means the error should come as mail id is already exists in Database…i need code in asp.net(c#).

By: saran

saran — Thu, 29 Nov 2012 09:24:38 +0000

By: Amit Kumar

Amit Kumar — Sat, 24 Nov 2012 08:16:03 +0000

Hi Pinal,
I want to learn about SQL Transactions.Please Help me.
Thanks
With Regards
Amit Kumar

By: madhivanan

madhivanan — Wed, 23 May 2012 10:02:37 +0000

Yes. Have you tried it?

By: jitin

jitin — Mon, 21 May 2012 09:31:11 +0000

yes it possible

By: SRIKANTH

SRIKANTH — Mon, 21 May 2012 05:12:32 +0000

Hi This is Srikanth,

Is Possible to give Primary Key and Unique Key in same table .

By: Gopi

Gopi — Thu, 19 Apr 2012 20:01:17 +0000

Hi Pinal,
I tried creating table with unique key as below and getting error when trying to insert one record with NULL value.
create table TEST (
id int not null,
name varchar(100)
)

ALTER TABLE TEST
ADD CONSTRAINT UNQ UNIQUE(ID)

INSERT INTO TEST VALUES(1,’A')
INSERT INTO TEST VALUES(NULL,’B')

Error Msg:
Msg 515, Level 16, State 2, Line 1
Cannot insert the value NULL into column ‘id’, table ‘CR6_DW.dbo.TEST’; column does not allow nulls. INSERT fails.
The statement has been terminated.

But unique key should allow one null value right?
Version used:
Microsoft SQL Server 2008 (RTM) – 10.0.1600.22 (X64) Jul 9 2008 14:17:44 Copyright (c) 1988-2008 Microsoft Corporation Enterprise Edition (64-bit) on Windows NT 6.1 (Build 7601: Service Pack 1) (VM)

By: Ranjeet Singh

Ranjeet Singh — Sat, 11 Feb 2012 08:07:09 +0000

how i update primary key value which have already foreign key value and i and i want to also update the record of foreign tables. tell me i am using ms sql 2005 server

By: Sourish Biswas

Sourish Biswas — Thu, 09 Feb 2012 13:55:49 +0000

I have checked
Primay Key does not allow NULL value

By: karthik

karthik — Fri, 27 Jan 2012 06:57:29 +0000

hai i need the command of without using constraint to drop the primary key

By: RK

RK — Mon, 02 Jan 2012 12:54:49 +0000

can you pls give real time examples of a just pk and a unique key which is not PK

By: Omkar Joshi

Omkar Joshi — Wed, 09 Nov 2011 09:08:20 +0000

i have two tables unit and item primary key(uid) of unit table is foreign key of item table
now i want to add the data in item table but due to foreign key problem my data is not inserted into item table in SQL server 2005

what is an alternate way to make insert query on database

By: Ashutosh

Ashutosh — Thu, 13 Oct 2011 14:59:58 +0000

perfect answer of unique value in Unique constraint

By: Hiren,

Hiren, — Sat, 01 Oct 2011 09:53:12 +0000

Hello Mr. Dave,
I read your articles so many time which are very fruitful for me,
From their I will get all most all the solutions of my query very easily , But I have some ambiguities
In my table. Lets give me solution for that .
My query is , may table is tab1(colname, tabname) here both are column name and multivalued
My table data is given as follows :
Opdate compupdtdtl
Cldate compupdtdtl
Totalamt loanstatus
[long list truncated]

My expected output is :
colname tab1 tab3 tab4
cldate cr_cp compupdtdlt rpl_emp_leave
loanid loantrans compupdtdtl loanstatus

Could you gime me solution of this problem ,
Anyone ?

By: Nilesh

Nilesh — Fri, 30 Sep 2011 07:17:35 +0000

Hi,
I have one question: I have one table Logs table lots of thread make entry in this table. The Primary key of this table in not identity column. I am getting primary key conflict error..what should i do now?

By: prabu

prabu — Thu, 29 Sep 2011 07:16:49 +0000

Really nice site…

By: madhivanan

madhivanan — Fri, 02 Sep 2011 08:05:00 +0000

Find the constraint name and use

alter table person drop constraint constraint_name

By: sarath

sarath — Thu, 01 Sep 2011 12:34:15 +0000

hello friends,help me on this

Create table person(p_id varchar(10) unique,
name_s varchar(20))

I have created a table person and set p_id as unique.
Now i want to delete the Unique for the P_id..
how can i do that in sql server… reply me asap