Question

The query:

UPDATE empPac
    SET quantityLimit = allocation,
        allocationStart = '"&allocationStart&"',
        nextUpdate = DATEADD(mm, allocationMonths, "&allocationStart&"),
        lastUpdate = GETDATE(),
        quantityIssued = 0,
        quantityShipped = 0
    WHERE allocation IS NOT NULL AND
          allocationMonths <> 0 AND
          (nextUpdate <= DATEADD(mm, "&checkCondition&", GETDATE()) OR
           nextUpdate IS NULL) AND
          empIdent in (select empIdent
                       from employee
                       where custIdent='"&custIdent&"')

What I want to do is add a conditional statement to the SET quantityLimit = allocation so that rather than having the WHERE allocation IS NOT NULL, I want it to have a conditional statement such as SET quantityLimit = ((allocation IS NULL) ? 0 : allocation)

Answer 1

You can use ISNULL():

SET quantityLimit = ISNULL(allocation, 0)

Equivalent functions for other databases are NVL() for Oracle and IFNULL() for MySQL and SQLite

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What you really should be using though is COALESCE() if you want to increase the portability of your code. COALESCE is part of the SQL-92 standard and widely supported across RDBMSes.