SQL Server Case Sensitive Queries

Recently, I’ve been tasked to create a data mask function.

They want:

  • A number will be a number
  • An upper case letter will be upper case
  • A lower case letter will be lower case
  • Punctuation and symbols will remain the same

An example would be:

123-00-6789 would become 456-88-4321
Mark would become Trxz

To enhance obfuscation, it will only be used one-way, and a 1:1 character swap is not necessary. Therefore, an uppercase A could be an upper case Z and an upper case X in the same sentence.

Thanks to this article at Novick Software, I was able to come up with the following example for future use.


--Create a table variable
DECLARE @Tbl TABLE (Name VARCHAR(100))

--Insert same name with different case
INSERT INTO @Tbl VALUES ('mark')
INSERT INTO @Tbl VALUES ('Mark')

–Gets the 1st (case-insensitive) result
SELECT DISTINCT Name FROM @Tbl

–Gets case-sensitive distinct results
SELECT DISTINCT Name COLLATE sql_latin1_general_cp1_cs_as FROM @Tbl

–Gets the distinct count (case-insensitive)
SELECT COUNT(DISTINCT Name) FROM @Tbl

–Gets the distinct count (case-sensitive)
SELECT COUNT(DISTINCT NAME COLLATE sql_latin1_general_cp1_cs_as) FROM @Tbl

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RJ writes custom Windows and Web applications using the Microsoft .NET framework, and enjoys solving problems with code, often while listening to a techno soundcloud stream. He hopes to one day write an application that many businesses will use.

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