Pattern match is a very important operation for search records base on character string columns. SQL Server 2005 offers the LIKE operator to perform pattern match operations in two formats:

target_string LIKE pattern

-- Returns TRUE

if the target string matches the pattern

target_string NOT LIKE pattern

-- Returns TRUE

if the target string does not match the pattern

Pattern match is a powerful operation. But you need to remember several rules:

* Pattern may contain predefined wildcard characters, similar to Unix Regular Expressions. But they are not the same.

* '%' is a wildcard character that matches any string of zero or more characters.

* '_' is a wildcard character that matches any single character.

* '_' is a wildcard character that matches any single character.

* '[abc]' is a wildcard character that matches any character listed inside the brackets.

* '[a-c]' is a wildcard character that matches any character in the range defined in the brackets.

* '[^abc]' is a wildcard character that matches any character not listed inside the brackets.

* '[^a-c]' is a wildcard character that matches any character not in the range defined in the brackets.