MySql – Criar função tipo SPLIT / Create function with SPLIT delimited strings

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   |
+-------+

fonte: http://blog.fedecarg.com/2009/02/22/mysql-split-string-function/

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