A heap is a table without a clustered index. read more at the below BOL link:

ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/udb9/html/72f63db6-7306-4c43-a73d-7eaa4ffe1f82.htm

Note: you will need to paste this link in BOL.
Start>Programs>Microsoft SQl Server 2005>Documentation and Tutorials> SQL Server Books Online

CREATE TABLE ORDER1 (
order_id bigint NOT NULL,
product_id int NOT NULL,
order_date datetime NOT NULL,
price decimal(21,2) NOT NULL,
PRIMARY KEY (order_id, product_id, order_date)
)

alter table Order1 drop constraint

actually wirite this syntax drop constraint and constraint name but above samplee how to identify the constraint name

alter table employee drop constraint id_pkey

I can make three primary keys in a table like

CREATE TABLE ORDER (
order_id bigint NOT NULL,
product_id int NOT NULL,
order_date datetime NOT NULL,
price decimal(21,2) NOT NULL,
———– columns —————

PRIMARY KEY (order_id, product_id, order_date)
)
GO

WELL, i can see three PK’s in SQLMS. Are these really 3 Pk’s or 1 PK or 2 composite keys?

As we create PK, we create an automatic Clustered index on the PK column.

What would be in this case?

Would there be 3 Clustered indexes here?

When i created this table and checked out the script by SQL server, i got script seems to have clustered index on a table instead of 3 above mentioned columns, so what does it mean?

i will appreciate your help..

Leo

How does this affect performance?

Thanks,

Dave

Thanks,
Jim

i ve created NC index on 2 tables, so while joining this two tbles, i get the result set, but while performing the Execution plan, the index of first table is considered, y so?

please reply me ASAP

thanks

Your article is very informative. As a reader i’ve few suggestions for you.

1) Please increase the font of SQL Code – gives more readability

2) Provide the color coding scheme of SQL Server so that we can easily understand the code snippet. There are may plugins for writers like Windows Live Writer to provide color schemes for code.

Anyway, your article is very informative. Thanks a lot.

Creating index is a real challenge for some one. one needs to be carefull while creating index.
answer to your question How to decide to create non clustered index is simple.
if u want to get only one record then create non cluseterd index but if your query needs a range of records then better to create clustred index.
actually u need to see which type of query is accssing data more oftenly and then desing index accodingly.

Case: the other day i have a table with 9 M records
it has a PK on TransactionNo.
but i found no body is concerend about TransactionNo, every one is accessing data on TransactionDate column, giving range like where TransactionDate >= getdate() -30 and TransactionDate <=getdate()

so my query was not using index properly. what i did i made PK ( whihc will be clustred index) on TransactionDate plus TransactionId.
and i am enjoying good performance.

Any one else can help me in this Case.

Hi Nidhi
Included Column Index is for non clustered index only. to some level these are Covering Index but by-pass the limitation of earlier version of sql server as these don’t conunt for the size of non clustered index.

How do we decide whether to create non clustered index on a column.?

I have a scenario where query response is taking nearly 2 minutes for <100 rows.
The major tables A B used in joining contain A-94million rows and B-4 million rows.

B.clientid primary key — 4million

A.clientid — distinct values — 2 million

So is it worth to create non clustered index on A.clientid column on A Table(94 million rows) ?

Will the join be faster and response better?
Appreciate your help !

Thanks
Sudha

Are the Included Column Index along with Clustered Index and Non-clustered Index same as covering indexes … or there is any difference in them ????

Im not able to figure out the difference between a composite index and an index with included columns? It would be helpful to me if you explan this. Thanks….