You don't have to interact with the managed code, because you can use LIKE:
SELECT * FROM
As your expression ends with + you can go with '%[^a-z0-9 .][^a-z0-9 .]%'
The SQL Server does not support regular expressions without the managed code. Though it is depending on the condition, this LIKE operator can be a choice, though, it lacks the flexibility that regular expressions can provide.
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