Determinant Databases MyBB

Forum Mybb supports three databases: PostgreSQL, SQLite and  MySQL. 
If you give a request http://localhost/forum/memberlist.php?letter=-1
 in the forum MyBB + PostgreSQL get the following error:
![errorpostgrsql](https://cloud.githubusercontent.com/assets/6502088/2556447/abf445c2-b6d4-11e3-9943-3acc894f02d4.JPG)
 in the forum MyBB + SQLite then:
![errorsqlite](https://cloud.githubusercontent.com/assets/6502088/2556458/e69156de-b6d4-11e3-9239-31f8585c256f.JPG)
MySQL database no error

Cause: The operator "regexps" espouse only MySQL