Tuesday, May 17, 2011

MySQL Split String Function


MySQL does not include a function to split a delimited string. However, it’s very easy to create your own function.

Create function syntax

A user-defined function is a way to extend MySQL with a new function that works like a native MySQL function.
CREATE [AGGREGATE] FUNCTION function_name
RETURNS {STRING|INTEGER|REAL|DECIMAL}
To create a function, you must have the INSERT privilege for the <mysql> database.

Split delimited strings

The following example function takes 3 parameters, performs an operation using an SQL function, and returns the result.
Function
CREATE FUNCTION SPLIT_STR(
  x VARCHAR(255),
  delim VARCHAR(12),
  pos INT
)
RETURNS VARCHAR(255)
RETURN REPLACE(SUBSTRING(SUBSTRING_INDEX(x, delim, pos),
       LENGTH(SUBSTRING_INDEX(x, delim, pos -1)) + 1),
       delim, '');
Usage
SELECT SPLIT_STR(string, delimiter, position)
Example
SELECT SPLIT_STR('a|bb|ccc|dd', '|', 3) as third;

+-------+
| third |
+-------+
| ccc   |
+-------+

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