Single-Column Format

Use the single-column format to pair one column with a single expression.


Single-Column Format

   .-,--------------------------------------.   
   V                                        |   
|----column-- = -+-expression-------------+-+-------------------|
                 +-(--singleton_select--)-+     
                 +-NULL-------------------+     
                 '-collection_var---------'

Element	Description	Restrictions	Syntax
column	Column to be updated	Cannot be a serial data type	Identifier
collection_var	Host or program variable	Must be declared as a collection data type	Language specific
expression	Returns a value for column	Cannot contain aggregate functions	Expression
singleton _select	Subquery that returns exactly one row	Returned subquery values must have a 1-to-1 correspondence with column list	SELECT statement

You can use this syntax to update a column that has a ROW data type.

You can include any number of "single column = single expression" terms. The expression can be an SQL subquery (enclosed between parentheses) that returns a single row, provided that the corresponding column is of a data type that can store the value (or the set of values) from the row that the subquery returns.

To specify values of a ROW-type column in a SET clause, see Updating ROW-Type Columns. The following examples illustrate the single-column format of the SET clause.

UPDATE customer
   SET address1 = '1111 Alder Court', city = 'Palo Alto',
      zipcode = '94301' WHERE customer_num = 103;

UPDATE stock
   SET unit_price = unit_price * 1.07;