SA0007 : Pattern starting with “%” in LIKE predicate

The topic describes the SA0007 analysis rule.

Message

Pattern starting with “%” in LIKE predicate

Description

This rule checks for usage of wildcard characters at the beginning of a word while searching using the LIKE keyword.

Usage of wildcard characters at the beginning of a LIKE pattern results in an index scan, which defeats the purpose of an index.

How to fix

Review the query and consider not using the LIKE predicate with pattern starting with “%”.

Scope

The rule has a Batch scope and is applied only on the SQL script.

Parameters
Name Description Default Value
IgnoreNonDMLStatements

Parameter specifies whether to ignore LIKE predicate with pattern starting with “%” when it appears inside non-DML statements.

yes
Remarks

The rule does not need Analysis Context or SQL Connection.

Effort To Fix
8 minutes per issue.
Categories

Performance Rules, Bugs

Additional Information

There is no additional info for this rule.

Example Test SQL
SQL
Copy
 1SELECT     LocationID
 2FROM       Locations
 3WHERE      Specialities LIKE '%pples' 
 4
 5SELECT     LocationID
 6FROM       Locations
 7WHERE      Specialities LIKE 'A%s'
 8
 9SELECT     LocationID
10FROM       Locations
11WHERE      Specialities LIKE 'Ap%'
12
13SELECT     LocationID
14FROM       Locations
15WHERE      Specialities LIKE '%pples' /*IGNORE:SA0007*/
16
17
18SELECT     LocationID
19FROM       Locations /*IGNORE:SA0007(STATEMENT)*/
20WHERE      Specialities LIKE '%pples' 
21
22IF db_name() like '%za%' 
23PRINT db_name()
Analysis Results
  Message Line Column
1 SA0007 : Pattern starting with “%” in LIKE predicate. 3 29
See Also

Other Resources

Analysis Rules