CODEWITHSUNDEEP
sqlregex
motanelu
motanelu

Reputation: 4025

Parse WHERE condition with regular expressions

I was wondering if anyone can help me with a regular expression - not my strongest point - to parse the WHERE part of a SQL statement. I need to extract the column names, either in "column" or "table.column" format. I'm using MySQL and PHP.

For example, parsing:

(table.column_a = '1') OR (table.column_a = '0')) 
AND (date_column < '2014-07-03') 
AND column_c LIKE '%my search string%'

should yield

table.column_a
table.column_b
date_column
column_c

Edit: clarification - the strings will be parsed in PHP with preg_* functions!

Thank you!

Upvotes: 2

Views: 1611

Answers (1)

zx81
zx81

Reputation: 41838

Assuming you are not doing this in SQL, you can use a regex like this:

[A-Za-z._]+(?=[ ]*(?:[<>=]|LIKE))

See regex demo.

This would work in Notepad++ and many languages.

Explanation

  • [A-Za-z._]+ matches the characters in your word (if you want to add digits, add 0-9
  • The lookahead (?=[ ]*(?:[<>=]|LIKE)) asserts that what follows is optional spaces (the brackets are optional, they make the space stand out), then one of the characters in this class [<>=] (an operator OR | LIKE
  • You can add operators inside [<>=], or tag them at the end with another alternation, e.g. |REGEXP

Reference

Upvotes: 4

Related Questions