Use '=' or LIKE to compare strings in SQL?

There's the (almost religious) discussion, if you should use LIKE or '=' to compare strings in SQL statements.

• Are there reasons to use LIKE?
• Are there reasons to use '='?
• Performance? Readability?

Solution 1:

LIKE and the equality operator have different purposes, they don't do the same thing:
= is much faster, whereas LIKE can interpret wildcards. Use = wherever you can and LIKE wherever you must.

SELECT * FROM user WHERE login LIKE 'Test%';

Sample matches:

TestUser1
TestUser2
TestU
Test

Solution 2:

To see the performance difference, try this:

SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name = B.name

SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name LIKE B.name

Comparing strings with '=' is much faster.