GROUP UNCONCAT

Dunno why you’d rather do this in SQL than in your application layer, but if you do, here’s one way to turn a delimited string of values back into multiple rows – just the opposite of GROUP_CONCAT:

SET @sourceString = 'a,b,c,d,e';
SET @sql = CONCAT('INSERT INTO t VALUES (\\'', REPLACE(@sourceString, ',', '\\'),(\\''), '\\')');
PREPARE myStmt FROM @sql;
EXECUTE myStmt;

Just to show what’s going on:

mysql> SELECT @sql;
+----------------------------------------------------+
| @sql                                               |
+----------------------------------------------------+
| INSERT INTO t VALUES ('a'),('b'),('c'),('d'),('e') |
+----------------------------------------------------+