COALESCE()

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COALESCE()

COALESCE() — Returns the first non-null argument, or null.

Synopsis

COALESCE( expression [, ... ] )

Description

The COALESCE() function takes multiple arguments and returns the value of the first argument that is not null, or — if all arguments are null — the function returns null.

Examples

The following example uses COALESCE to perform two functions:

  • Replace possibly null column values with placeholder text

  • Return one of several column values

In the second usage, the SELECT statement returns the value of the column State, Province, or Territory depending on the first that contains a non-null value. Or the function returns a null value if none of the columns are non-null.

SELECT lastname, firstname, 
   COALESCE(address,'[address unkown]'),
   COALESCE(state, province, territory),
   country FROM users ORDER BY lastname;