SQL Server check case-sensitivity?

If you installed SQL Server with the default collation options, you might find that the following queries return the same results: 

CREATE TABLE mytable 
( 
    mycolumn VARCHAR(10) 
) 
GO 

SET NOCOUNT ON 

INSERT mytable VALUES('Case') 
GO 

SELECT mycolumn FROM mytable WHERE mycolumn='Case' 
SELECT mycolumn FROM mytable WHERE mycolumn='caSE' 
SELECT mycolumn FROM mytable WHERE mycolumn='case'

You can alter your query by forcing collation at the column level: 

SELECT myColumn FROM myTable  
    WHERE myColumn COLLATE Latin1_General_CS_AS = 'caSE' 

SELECT myColumn FROM myTable  
    WHERE myColumn COLLATE Latin1_General_CS_AS = 'case' 

SELECT myColumn FROM myTable  
    WHERE myColumn COLLATE Latin1_General_CS_AS = 'Case' 

-- if myColumn has an index, you will likely benefit by adding 
-- AND myColumn = 'case' 

SELECT DATABASEPROPERTYEX('<database name>', 'Collation')

As changing this setting can impact applications and SQL queries, I would isolate this test first. From SQL Server 2000, you can easily run an ALTER TABLE statement to change the sort order of a specific column, forcing it to be case sensitive. First, execute the following query to determine what you need to change it back to: 

EXEC sp_help 'mytable'

The second recordset should contain the following information, in a default scenario:

Column_Name Collation

mycolumn SQL_Latin1_General_CP1_CI_AS

Whatever the 'Collation' column returns, you now know what you need to change it back to after you make the following change, which will force case sensitivity: 

ALTER TABLE mytable 
    ALTER COLUMN mycolumn VARCHAR(10) 
    COLLATE Latin1_General_CS_AS 
GO 



SELECT mycolumn FROM mytable WHERE mycolumn='Case' 
SELECT mycolumn FROM mytable WHERE mycolumn='caSE' 
SELECT mycolumn FROM mytable WHERE mycolumn='case'

If this screws things up, you can change it back, simply by issuing a new ALTER TABLE statement (be sure to replace my COLLATE identifier with the one you found previously): 

ALTER TABLE mytable 
    ALTER COLUMN mycolumn VARCHAR(10) 
    COLLATE SQL_Latin1_General_CP1_CI_AS

If you are stuck with SQL Server 7.0, you can try this workaround, which might be a little more of a performance hit (you should only get a result for the FIRST match): 

SELECT mycolumn FROM mytable WHERE 
    mycolumn = 'case' AND 
    CAST(mycolumn AS VARBINARY(10)) = CAST('Case' AS VARBINARY(10)) 

SELECT mycolumn FROM mytable WHERE 
    mycolumn = 'case' AND 
    CAST(mycolumn AS VARBINARY(10)) = CAST('caSE' AS VARBINARY(10)) 

SELECT mycolumn FROM mytable WHERE 
    mycolumn = 'case' AND 
    CAST(mycolumn AS VARBINARY(10)) = CAST('case' AS VARBINARY(10)) 

-- if myColumn has an index, you will likely benefit by adding 
-- AND myColumn = 'case'

Collation can be set at various levels:

  1. Server
  2. Database
  3. Column

So you could have a Case Sensitive Column in a Case Insensitive database. I have not yet come across a situation where a business case could be made for case sensitivity of a single column of data, but I suppose there could be.

Check Server Collation

SELECT SERVERPROPERTY('COLLATION')

Check Database Collation

SELECT DATABASEPROPERTYEX('AdventureWorks', 'Collation') SQLCollation;

Check Column Collation

select table_name, column_name, collation_name
from INFORMATION_SCHEMA.COLUMNS
where table_name = @table_name

Tags:

Sql

Sql Server

Tsql

Case Sensitive

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