Checksum calculates a "fingerprint" of the supplied string argument. It is used for data verification. It returns INT. Here are some examples:

select CHECKSUM('Joanna Smith')

-- 1017174263

select CHECKSUM('Joanna Smitg')

-- 1017174262

select CHECKSUM('Joanna Smith lives in New York City')

GO

-- 167919681

-- Random number generation in conjunction with NEWID() function

select CHECKSUM(newid())

GO 3

-- -123549627

-- 15673588

-- 1263227242

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-- Generating random phone numbers - data obfuscation

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DECLARE @Phone char(10) = '2123458200'

DECLARE @NewPhone char(10) = left(@Phone,3)+

        LEFT(convert(varchar,ABS(CHECKSUM(newid()))+'0000000'),7)

SELECT @Phone, @NewPhone

GO 5

-- 2123458200     2121631287

-- 2123458200     2121470137

-- 2123458200     2121441560

-- 2123458200     2122004110

-- 2123458200     2121007063

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