[sql] Is the LIKE operator case-sensitive with MSSQL Server?

In the documentation about the LIKE operator, nothing is told about the case-sensitivity of it. Is it? How to enable/disable it?

I am querying varchar(n) columns, on an Microsoft SQL Server 2005 installation, if that matters.

All this talk about collation seem a bit over-complicated. Why not just use something like:

IF UPPER(@@VERSION) NOT LIKE '%AZURE%'

Then your check is case insensitive whatever the collation

Try running,

SELECT SERVERPROPERTY('COLLATION')

Then find out if your collation is case sensitive or not.

You have an option to define collation order at the time of defining your table. If you define a case-sensitive order, your LIKE operator will behave in a case-sensitive way; if you define a case-insensitive collation order, the LIKE operator will ignore character case as well:

CREATE TABLE Test (
    CI_Str VARCHAR(15) COLLATE Latin1_General_CI_AS -- Case-insensitive
,   CS_Str VARCHAR(15) COLLATE Latin1_General_CS_AS -- Case-sensitive
);

Here is a quick demo on sqlfiddle showing the results of collation order on searches with LIKE.

The like operator takes two strings. These strings have to have compatible collations, which is explained here.

In my opinion, things then get complicated. The following query returns an error saying that the collations are incompatible:

select *
from INFORMATION_SCHEMA.TABLES
where 'abc' COLLATE SQL_Latin1_General_CP1_CI_AS like 'ABC' COLLATE SQL_Latin1_General_CP1_CS_AS

On a random machine here, the default collation is SQL_Latin1_General_CP1_CI_AS. The following query is successful, but returns no rows:

select *
from INFORMATION_SCHEMA.TABLES
where 'abc' like 'ABC' COLLATE SQL_Latin1_General_CP1_CS_AS

The values "abc" and "ABC" do not match in a case-sensitve world.

In other words, there is a difference between having no collation and using the default collation. When one side has no collation, then it is "assigned" an explicit collation from the other side.

(The results are the same when the explicit collation is on the left.)

You can easy change collation in Microsoft SQL Server Management studio.

• right click table -> design.
• choose your column, scroll down i column properties to Collation.
• Set your sort preference by check "Case Sensitive"

You can change from the property of every item.

If you want to achieve a case sensitive search without changing the collation of the column / database / server, you can always use the COLLATE clause, e.g.

USE tempdb;
GO
CREATE TABLE dbo.foo(bar VARCHAR(32) COLLATE Latin1_General_CS_AS);
GO
INSERT dbo.foo VALUES('John'),('john');
GO
SELECT bar FROM dbo.foo 
  WHERE bar LIKE 'j%';
-- 1 row

SELECT bar FROM dbo.foo 
  WHERE bar COLLATE Latin1_General_CI_AS LIKE 'j%';
-- 2 rows

GO    
DROP TABLE dbo.foo;

Works the other way, too, if your column / database / server is case sensitive and you don't want a case sensitive search, e.g.

USE tempdb;
GO
CREATE TABLE dbo.foo(bar VARCHAR(32) COLLATE Latin1_General_CI_AS);
GO
INSERT dbo.foo VALUES('John'),('john');
GO
SELECT bar FROM dbo.foo 
  WHERE bar LIKE 'j%';
-- 2 rows

SELECT bar FROM dbo.foo 
  WHERE bar COLLATE Latin1_General_CS_AS LIKE 'j%';
-- 1 row

GO
DROP TABLE dbo.foo;