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Editorial Team
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Asked: 2026-06-15T00:56:48+00:00

Recently, we have changed from MySQL to PostgreSQL. Most of the queries have been

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Recently, we have changed from MySQL to PostgreSQL. Most of the queries have been translated except for the ones with the Mysql ‘REGEXP’ keyword:

MySQL (prepared statement):
SELECT * FROM table WHERE ? REGEXP identifier;

We have a ‘table’, and one of the columns is called ‘identifier’. This ‘identifier’ column contains the actual regular expression pattern.

So, instead of ‘hard-coding’ the regexp pattern in the query, it looks-up the identifier column for the pattern.

In Postgresql, we need to use the ‘~’ keyword instead of the ‘REGEXP’ one (which is MySQL only), but with Postgresql I cannot seem to extract the pattern from a column.

I’ve tried following queries without success:

SELECT * FROM table WHERE 'test' ~ "identifier";
ERROR:  invalid regular expression: parentheses () not balanced


SELECT * FROM table WHERE "identifier" ~ 'test';
-> no results

for testing purposes I created a number of records where the “identifier” column contains ‘.*’ as value (regular expression for match everything), but still I do not get the appropriate result.

Help is very much welcome, thank you!

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1 Answer

  1. Editorial Team

    Maybe the problem is in one of the regexp strings? (As the error string says)

    I’ve tested

    SELECT *
FROM table1 t
WHERE 'cat' ~ t.reg;

    And it works for me. Here is my SQL Fiddle. http://sqlfiddle.com/#!12/f245c/3

    The problem can be in different regexp interpretation. Details about postgresql regexp here http://www.postgresql.org/docs/current/static/functions-matching.html

    UPD Also read http://www.postgresql.org/docs/current/interactive/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS for detail about postgresql strings. You need this to write regexp correctly.

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