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    Categories: Conditional


    Compares two expressions. If the values in each expression are equal, returns NULL and, if they are not equal, returns the value of the first expression.


    NULLIF(expression1, expression2) → same as input type

    • expression: The expressions can be any data type, however all the expressions contained in the argument must be of the same type.


    NULLIF example
    SELECT NULLIF(user_id, customer_id)
    -- user_id