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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:
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The NULLIF function will convert any column value with only whitespace into a NULL value. Works for T-SQL and SQL Server 2008 & up. SELECT [column_name] FROM [table_name] WHERE NULLIF([column_name], '') IS NULL
This tutorial introduces you to the SQL NULLIF function and shows you how to add the if-else condition to your SQL queries.
Returns a null value if the two specified expressions are equal. For example, SELECT NULLIF(4,4) AS Same, NULLIF(5,7) AS Different; returns NULL for the first column (4 and 4) because the two input values are the same.
The NULLIF expression comes in handy when you’re working with legacy data that contains a mixture of null and empty strings in a column. Consider the following example. First, create a new table named sales.leads to store the sales leads:
8 maj 2022 · NULLIF() evaluates the current value of the expressions. Therefore, if we pass an expression like this: SELECT NULLIF( 24, 2 * 12 ); We get this: NULL. 2 multiplied by 12 is 24, and so the two arguments are equivalent. Here’s what happens if we change the second argument: SELECT NULLIF( 24, 3 * 12 ); Result: 24. The first argument is returned.
You would use the SQL NULLIF function when you want to replace a value with NULL in your query result if it matches a specified condition. NULLIF is particularly useful when you need to handle equality as a distinct case, such as when you want to hide or suppress certain results in your query.
