How Does SQL Server's LIKE Operator Handle Case Sensitivity?

SQL Server's LIKE Operator: Case Sensitivity Explained

The SQL Server LIKE operator's case sensitivity isn't inherent; it's governed by the column's collation settings. Let's explore how collations impact case-sensitive comparisons.

Collation: The Key to Case Sensitivity

Collations define the rules for data interpretation and comparison within a SQL Server instance. The default collation applies at the instance level, but this can be overridden at the database or even individual column level. Column-level collation takes precedence.

Controlling Case Sensitivity

To achieve case-sensitive comparisons, define your column using a case-sensitive collation (e.g., SQL_Latin1_General_CP1_CS_AS). Conversely, for case-insensitive comparisons, use a case-insensitive collation (e.g., SQL_Latin1_General_CP1_CI_AS).

Verifying Collation Settings

Check collation settings using these queries:

• Instance Collation: SELECT SERVERPROPERTY('collation');
• Database Collation: SELECT DATABASEPROPERTYEX('database_name', 'collation');
• Column Collation: Examine the COLLATE clause in the column's definition.

Modifying Collations (Use with Caution)

While you can alter a column's collation using ALTER TABLE, this is resource-intensive and should be avoided in production unless absolutely necessary. The syntax is:

ALTER TABLE table_name
ALTER COLUMN column_name VARCHAR(10) COLLATE new_collation;

Summary

In SQL Server, the LIKE operator's case sensitivity is entirely dependent on the column's collation. Careful collation management ensures predictable and controlled case-sensitive behavior in your database operations.

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