CODEWITHSUNDEEP
sql-servert-sql
Peter Rivas
Peter Rivas

Reputation: 13

T-SQL query assistance two single quotes in where clause

I've been trying to understand this t-sql query but I'm not sure what the 'where' clause means. Here is the query:

UPDATE s
SET s.ID1 = p.ID1,
    s.FIRST_NAME = p.FIRST_NAME,
    s.LAST_NAME  = p.LAST_NAME,
    s.DEPT_DESCR = p.DEPT_DESCR
FROM dbo.DIRECTORY_VW S
JOIN ps.STAGING_DIRECTORY_VW P ON s.ID = p.ID
WHERE p.ID <> ''

I understand the query updates ID1, FIRST_NAME, LAST_NAME, and DEPT_DESCR values on the DIRECTORY_VW view with the values from the STAGING_DIRECTORY_VW, where the ID is the same, but what does the <> '' mean? <> is NOT EQUAL in T-SQL but I'm having trouble finding what two single quotes do.

Thanks in advance!

Upvotes: 0

Views: 84

Answers (2)

squillman
squillman

Reputation: 13641

'' in tsql is an empty string. It's a string that is not NULL, but also has nothing in it.

So,

someVal <> '' is not the same as someVal IS NOT NULL

Upvotes: 2

pete
pete

Reputation: 25091

Two back-to-back apostrophes ('') is a common way of representing an empty string, so the WHERE clause is simply where p.ID is not equal to an empty string.

Upvotes: 0

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