/usr/man/cat.l/update.l.Z(/usr/man/cat.l/update.l.Z)

NAME

       UPDATE - update rows of a table

SYNOPSIS

       UPDATE [ ONLY ] table SET column = { expression | DEFAULT } [, ...]
           [ FROM fromlist ]
           [ WHERE condition ]

DESCRIPTION

       UPDATE  changes  the  values  of the specified columns in all rows that
       satisfy the condition. Only the columns to be  modified  need  be  men-
       tioned in the statement; columns not explicitly SET retain their previ-
       ous values.

       By default, UPDATE will update rows in the specified table and all  its
       subtables. If you wish to only update the specific table mentioned, you
       must use the ONLY clause.

       You must have the UPDATE privilege on the table to update it,  as  well
       as  the  SELECT  privilege  to  any  table whose values are read in the
       expressions or condition.

PARAMETERS

       table  The name (optionally schema-qualified) of the table to update.

       column The name of a column in table.

       expression
              An expression to assign to the column. The  expression  may  use
              the old values of this and other columns in the table.

       DEFAULT
              Set  the  column  to its default value (which will be NULL if no
              specific default expression has been assigned to it).

       fromlist
              A list of table expressions, allowing columns from other  tables
              to appear in the WHERE condition and the update expressions.

       condition
              An  expression  that returns a value of type boolean.  Only rows
              for which this expression returns true will be updated.

OUTPUTS

       On successful completion, an UPDATE command returns a  command  tag  of
       the form

       UPDATE count

       The count is the number of rows updated. If count is 0, no rows matched
       the condition (this is not considered an error).

EXAMPLES

       Change the word Drama to Dramatic in  the  column  kind  of  the  table
       films:

       UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';

       Adjust temperature entries and reset precipitation to its default value
       in one row of the table weather:

       UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
         WHERE city = 'San Francisco' AND date = '2003-07-03';

COMPATIBILITY

       This command conforms to the SQL standard. The FROM clause is  a  Post-
       greSQL extension.

SQL - Language Statements         2003-11-02                         UPDATE(l)