This document provides tips for optimizing Transact-SQL queries and stored procedures. It recommends restricting result sets using WHERE and SELECT clauses, using views and stored procedures instead of ad hoc queries, and avoiding cursors and unnecessary DISTINCT, HAVING and UNION clauses. It also suggests optimizing indexes, using appropriate join types, and monitoring queries with execution plans to ensure efficient indexing strategies.

1. Database Optimization Tips
Nikhildas.P.C
nikhildasp@gmail.com

2. Topics
1. Transact – SQL optimization tips
2. SQL Server optimization tips

3. 1. Transact – SQL optimization tips
1. Try to restrict the queries result set by
using the WHERE clause.
2. Try to restrict the queries result set by
returning only the particular columns
from the table, not all table’s columns.
3. Use views and stored procedures
instead of heavy-duty queries.
4. Try to avoid using SQL Server cursors,
whenever possible.
5. If you need to return the total table’s
row count, you can use alternative way
instead of SELECT COUNT(*) statement.

4. 1. Transact – SQL optimization tips
1. Use table variables instead of temporary
tables.
2. Try to avoid the HAVING clause,
whenever possible.
3. Try to avoid using the DISTINCT clause,
whenever possible.
4. Include SET NOCOUNT ON statement
into your stored procedures to stop the
message indicating the number of rows
affected by a T-SQL statement.

5. 1. Transact – SQL optimization tips
1. Use the select statements with TOP
keyword or the SET ROWCOUNT
statement, if you need to return only
the first n rows.
2. Use the FAST number_rows table hint if
you need to quickly return
‘number_rows’ rows.
3. Try to use UNION ALL statement instead
of UNION, whenever possible.
4. Do not use optimizer hints in your
queries.

6. 1. Transact – SQL optimization tips
1. Try to avoid using DDL (Data Definition
Language) statements inside your
stored procedure.
2. If you have a very large stored
procedure, try to break down this stored
procedure into several sub-procedures,
and call them from a controlling stored
procedure.
3. Use the sp_executesql stored procedure
instead of the EXECUTE statement.
4. Try to use constraints instead of
triggers, whenever possible.

7. 1. Transact – SQL optimization tips
1. Don’t use the prefix “sp_” in the stored
procedure name if you need to create a
stored procedure to run in a database
other than the master database.
2. Consider returning the integer value as
an RETURN statement instead of an
integer value as part of a recordset.
3. Call stored procedure using its fully
qualified name.
4. Try to avoid using temporary tables
inside your stored procedure.

8. 1. Transact – SQL optimization tips
1. Include the SET ANSI_WARNINGS ON,
SET ANSI_NULLS ON statement into
your stored procedures.
2. Always add an Debug parameter to your
stored procedures. This can be a BIT
data type.
3. If your stored procedure always returns
a single row resultset, consider
returning the resultset using OUTPUT
parameters instead of a SELECT
statement

9. 1. Transact – SQL optimization tips
1. Use Alias name with Column Name in
select statement.
2. Use appropriate Join (Inner,Outer,Self)
3. Use Where condition before Joining (Eg.
Select D.CustName from ( select ID
from CustMaster where CustID = 12346
) M Inner Join CustDetails D on M.ID =
D.ID
4. Use Between instead of >= <=, if
possible
5. Use Order by,where,join For Indexed
Column.
6. Avoid functions with WHERE clause.

10. 1. Transact – SQL optimization tips
1. Do not use column numbers in the
ORDER BY clause - Eg. Order by 2
2. ANSI-Standard Join clauses instead of
the old style joins.
3. Do not call functions repeatedly within
your stored procedures, triggers,
functions and batches.(Eg. Len (Name)
call the LEN function once, and store the
result in a variable for later use.)
4. If you need to delete all tables rows,
consider using TRUNCATE TABLE
instead of DELETE command.

11. 1. Transact – SQL optimization tips
1. Do not let your front-end applications
query/manipulate the data directly
using SELECT or INSERT/UPDATE /
DELETE statements. Instead, create
stored procedures and let your
applications access these stored
procedures.
2. Use the graphical execution plan in
Query Analyzer or SHOWPLAN_TEXT or
SHOWPLAN_ALL commands to analyze
your queries. Make sure your queries do
an "Index seek" instead of an "Index
scan" or a "Table scan."

12. 1. Transact – SQL optimization tips
1. Don't Compare null value with =,<>
(Eg.IF @DDate <> NULL) Use – IF
@Ddate Is Null
2. A Table should have
. primary key
. minimum of one clustered index
. appropriate amount of non-clustered
index
. Non-clustered index should be created
on columns of table based on query
which is running

13. 1. Transact – SQL optimization tips
1. Following priority order should be
followed when any index is created a)
WHERE clause, b) JOIN clause, c)
ORDER BY clause, d) SELECT clause.
2. Check if there is at least 30% HHD is
empty – it improves the performance a
bit.
3. Use Error Tracing in SP,Fn,trigger (Eg.
Try Catch or @@ERROR global variable)
4. Use BEGIN TRANSACTION, COMMIT
TRANSACTION and ROLLBACK
TRANSACTION.

14. 1. Transact – SQL optimization tips
1. Avoid using dynamic SQL statements
inside stored procedures, i.e., Do not
use SQL statements to create SQL
statements.
2. Be careful while SELECT-ing strings with
LIKE clause. If it is not used wisely, it
will give rise to performance problems.
3. Use Update Statistics with bulk
insertion, deletion query.
4. Use Covering indexes.

15. 1. Transact – SQL optimization tips
1. Use indexed Views.
2. Use Apply clause, if Possible
3. Use Computed Column
4. Use Profiler,Database engine Tuning
advisor,Execution plan to monitor
performance.
5. Try to write code neatly with proper
commenting and program flow picture.

16. THANKS