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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.
The NULLIF() function returns NULL if two expressions are equal, otherwise it returns the first expression. Syntax
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
SQL NULLIF examples. The following statement returns NULL because 100 is equal to 100. SELECT NULLIF (100, 100); Code language: SQL (Structured Query Language) (sql) The following statement returns 100 because 100 is less than 200, the NULLIF function returns the first argument which is 100.
The following example creates a budgets table, loads data, and uses NULLIF to return a null if current_year is null or contains the same data as previous_year.
SQL Server NULLIF examples. Let’s take some examples of using the NULLIF expression. Using NULLIF expression with numeric data examples. This example returns NULL because the first argument equals the second one: SELECT NULLIF (10, 10) result; Code language: SQL (Structured Query Language) (sql) Here is the output:
15 sty 2021 · SQL NULLIF expression compares two expression and returns a null value if the two specified expressions are equal, else it returns the first expression. NULLIF expression is equivalent to a searched CASE expression in which the two expressions are equal and the resulting expression is NULL.
