Convert SQL where clause to regex

Asked Oct 07 '20 at 20:49

Active Oct 07 '20 at 20:49

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I have the following SQL statement:

# WHERE
field LIKE '%ig%' AND field LIKE '%ru%'

What would be the correct way to translate this to a regex? My thought was because the ordering (in sql) doesn't matter, it'd each AND-ed %term% would translate to a positive lookahead:

(?=.*ig)(?=.*ru).+

Is there a better approach to this or is that normally how the above is translated?

asked Oct 07 '20 at 20:49

samuelbrody1249

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Anchor the match at the start of the string, add `^` at the start. It is not necessary if you use `re.search` or `re.match` though. – Wiktor Stribiżew Oct 07 '20 at 20:51
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@WiktorStribiżew out of curiosity, why are anchors important here if it's just a wildcard match on the entire text string? – samuelbrody1249 Oct 07 '20 at 20:52
See [***Lookarounds (Usually) Want to be Anchored***](https://www.rexegg.com/regex-lookarounds.html#anchor). – Wiktor Stribiżew Oct 07 '20 at 20:56
@WiktorStribiżew I see, but that website has some screwed-up font colors that I can't really read...could you provide the gist of it? – samuelbrody1249 Oct 07 '20 at 21:36
If the regex method tests each position inside a string, there will be redundant overhead. If you use a single matching method, it is OK to omit the `^` anchor. – Wiktor Stribiżew Oct 07 '20 at 21:41

Convert SQL where clause to regex

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