![]() ![]() When the first argument is not null, the second argument is returned. This allows us to provide a different value for non- null values. Oracle’s NVL2() function accepts three arguments. Oracle Database also has an NVL2() function that provides extra functionality to NVL(). Oracle Database has the NVL() function that does the same thing that IFNULL() does in other RDBMSs. If the argument is null, ISNULL() returns 1, otherwise it returns 0. In those RDBMSs, ISNULL() accepts just one argument. Other RDBMSs (such as MySQL, MariaDB, and Oracle) also have an ISNULL() function, but for a different purpose. If you’ve used other RDBMSs, you might be confused about SQL Server’s implementation of ISNULL(). Result: Error: Divide by zero error encountered. SQL Server doesn’t have an IFNULL() function, but it does have the ISNULL() function that does the same thing that IFNULL() does in the RDBMSs mentioned above.Īnd here it is when the first argument is a non- null value: SELECT ISNULL( 2 * 3, 'Horse' ) īut if we try to divide by zero we get an error: SELECT ISNULL( 2 / 0, 'Horse' ) That’s because the first argument is null, and so it progressed to the second argument (which also resolves to null). Here it is again with the null constant as the first argument: SELECT IFNULL( null, 1 / 0 ) That’s because the first argument is non- null. In this case MySQL doesn’t return a warning like before. To demonstrate this, here it is on its own: SELECT IFNULL( 'Horse', 1 / 0 ) The second argument is not even evaluated in this case. In the third column, the first argument is a non- null value and so it is returned. In the second column, the expression returns a non-null value, and so it is returned. Therefore the second argument is returned. In the first column I tried to divide by zero, which results in a null value in MySQL (and a warning). IFNULL() evaluates the current value of any expression: SELECT If the first argument is not null, then the first argument is returned. If the first one is null, then the second argument is returned. How it works is, the IFNULL() function accepts two arguments. | IFNULL( null, 'Dog' ) | IFNULL( 'Horse', 'Dog' ) | IFNULL( 'Horse', null ) | Here’s an example of how IFNULL() works in those RDBMSs: SELECT Example of IFNULL()Īs mentioned, RDBMSs such as MySQL, MariaDB, and SQLite include an IFNULL() function for replacing null values with another value. Other RDBMSs, such as SQL Server, Oracle, and PostgreSQL provide similar functionality via functions of a different name. In particular, MySQL, MariaDB, and SQLite each have an IFNULL() function that replaces any null values with another value. Some RDBMSs provide an IFNULL() function that can be used when dealing with potentially null values. ![]()
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