Multi-Pattern Replacement with SQL Server

Kevin Feasel

2019-04-22

T-SQL

Hugo Kornelis has a pattern matching problem to solve:

The actual use case and the list of patterns that I had to remove are considered a confidential competitive advantage by my client, so I will just make up a list here to illustrate the problem. In this fake requirement, the following patterns must all be removed if anywhere in the string: “[email protected]@%”, “@@%”, “[email protected]%”, “@%”, “No.X#X”, and “^^^”. Also, “@X” needs to be removed when at the end of the string. In these patterns, @ is a placeholder for a numeric symbol, X for an alphabetic symbol, and # for an alphabetic or numeric symbol. All other symbols are to be taken literally. (So “%” is the percent mark, not the LIKE pattern for any character!).

This is a problem for regular expressions, but without built-in regular expressions (and I’d guess no desire to use the CLR), Hugo gives us a workable solution.

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