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25 lut 2016 · The following query is not returning values for CurrentVisitor in my ms access 2010 database: SELECT ClientNumber, MAX(LastVisitDate) AS LastVisitStart. FROM VisitsTable. GROUP BY ClientNumber) AS t. I think the reason is that the check for null in the If() operation is not written correctly.
Definition and Usage. The NULLIF () function returns NULL if two expressions are equal, otherwise it returns the first expression. Syntax. NULLIF (expr1, expr2) Parameter Values. Technical Details. More Examples. Example. Compare two expressions: SELECT NULLIF('Hello', 'Hello'); Try it Yourself » Example. Compare two expressions:
Transact-SQL syntax conventions. Syntax NULLIF ( expression , expression ) Arguments. expression Is any valid scalar expression. Return Types. Returns the same type as the first expression. NULLIF returns the first expression if the two expressions are not equal. If the expressions are equal, NULLIF returns a null value of the type of the first ...
8 maj 2022 · Syntax. The syntax goes like this: NULLIF (V1, V2) This is equivalent to the following CASE expression: CASE WHEN V1=V2 THEN NULL ELSE V1 END. Example. Here’s an example to demonstrate: SELECT NULLIF( 12, 12 ); Result: NULL. In this case, both arguments are identical and so the result is NULL.
The syntax for the NULLIF function in SQL Server (Transact-SQL) is: NULLIF ( expression1, expression2 ) Parameters or Arguments. expression1, expression2. The expressions that will be compared. Values must be of the same datatype. Note. expression1 can be an expression that evaluates to NULL, but it can not be the literal NULL. Applies To.
Summary: in this tutorial, you will learn how to use the SQL Server NULLIF expression to return NULL if the first argument equals to the second one. The NULLIF expression accepts two arguments and returns NULL if two arguments are equal.
The SQL NULLIF function is used to compare two expressions or values and return NULL if they are equal. It provides a way to handle specific cases where you want to treat equality as a special condition by substituting it with a NULL value.
