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UPDATE
UPDATE
Syntax
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Updates the rows and columns of the specified table with the given values for rows that satisfy
the search_condition.
UPDATE table_name
SET assignment [, assignment ] , ...
[ WHERE search_condition ] ;
assignment:
This is the syntax for assignment:
Syntax
column = { expr | NULL }
| ( column [, column ] , ... ) = ( expr [, expr ] )
| ( column [, column ] , ... ) = ( query_expression )
Notes • If you specify the optional WHERE clause, only rows that satisfy the search_condition are
updated. If you do not specify a WHERE clause, all rows of the table are updated.
• If the expressions in the SET clause are dependent on the columns of the target table, the
expressions are evaluated for each row of the table.
• If a query expression is specified on the right-hand side of an assignment, the number of
expressions in the first SELECT clause of the query expression must be the same as the
number of columns listed on the left-hand side of the assignment.
• If a query expression is specified on the right-hand side of an assignment, the query
expression must return one row.
• If a table has check constraints and if the columns to be updated are part of a check
expression, then the check expression is evaluated. If the result of the evaluation is FALSE,
the UPDATE statement fails.
• If a table has primary or candidate keys and if the columns to be updated are part of the
primary or candidate key, SQL checks to determine if there is a corresponding row in the
referencing table. If there is a corresponding row the UPDATE operation fails.
• Column names in the SET clause do not need a table_name qualifier. Since an UPDATE
statement affects a single table, columns in the SET clause are implicitly qualified to the
table_name identified in the UPDATE clause.
The following is an example of an UPDATE statement: