Question

Consider the following table :

mysql> select * from test;
+---------+
| col     |
+---------+
| ^test$  |
| tes$()t |
| X$%[    |
| test$   |
| ^test   |
| test    |
| [       |
+---------+
7 rows in set (0.04 sec)

It contains valid and invalid patterns.

If I do :

mysql> select * from test where 'test' regexp col;
+--------+
| col    |
+--------+
| ^test$ |
| test$  |
| ^test  |
| test   |
+--------+
4 rows in set (0.04 sec)

I get all rows with a pattern matching ‘test’, and all other rows (including invalid patterns) are just ignored.

Now, if I do an invalid request directly, I get a pattern syntax error :

mysql> select * from test where 'test' regexp '[';
ERROR 1139 (42000): Got error 'brackets ([ ]) not balanced' from regexp

Is there a way (without another table) to force MySQL to ignore those errors (will give an empty result for example) ?

Answer 1

Okey I found a working solution, that’s tricky but that work :

SELECT * FROM test WHERE 'test' REGEXP RIGHT(CONCAT(col, '['), LENGTH('['));

Replace ‘[‘ by your regexp pattern. May be useful if you allow your customers to use regexps.