UPDATE v17

Name

UPDATE — Update rows of a table.

Synopsis

edb=# \h UPDATE 
Command:     UPDATE
Description: update rows of a table
Syntax:
[ WITH [ RECURSIVE ] with_query [, ...] ]
UPDATE [ <optimizer_hint> ][ ONLY ] <table_name>[@<dblink> ] [ * ] [ [ AS ] alias ]
    SET { { <column_name> = { <expression> | DEFAULT } |
            ( <column_name> [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) |
            ( <column_name> [, ...] ) = ( sub-SELECT )
          } [, ...] |
          ROW = <row_or_record_var>
        }
    [ FROM <from_item> [, ...] ]
    [ WHERE <condition> | WHERE CURRENT OF <cursor_name> ]
    [ RETURNING <return_expression> [, ...]
      { INTO { <record> | <variable> [, ...] }
      | BULK COLLECT INTO <collection> [, ...] } ]

URL: https://www.postgresql.org/docs/15/sql-update.html
     https://www.enterprisedb.com/docs

Description

UPDATE changes the values of the specified columns in all rows that satisfy the condition. You need to mention only the columns you want to modify in the SET clause. Columns not explicitly modified retain their values.

SET ROW enables us to update a target record using a record type variable or row type objects. The record or row used, must have compatible data types with the table's columns in order.

You can specify the RETURNING INTO { record | variable [, ...] } clause only in an SPL program. In addition, the result set of the UPDATE command must not return more than one row. Otherwise an exception is thrown. If the result set is empty, then the contents of the target record or variables are set to null.

In an SPL program, you can specify the RETURNING BULK COLLECT INTO collection [, ...] clause only if you use the UPDATE command. If you specify more than one collection as the target of the BULK COLLECT INTO clause, then each collection must consist of a single scalar field. That is, collection can't be a record. The result set of the UPDATE command can contain zero or more rows. return_expression evaluated for each row of the result set becomes an element in collection starting with the first element. Any existing rows in collection are deleted. If the result set is empty, then collection is empty.

You need the UPDATE privilege on the table to update it. You also need the SELECT privilege to any table whose values are read in expression or condition.

Parameters

optimizer_hint

Comment-embedded hints to the optimizer for selecting an execution plan.

table

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

dblink

Database link name identifying a remote database. See the CREATE DATABASE LINK command for information on database links.

column

The name of a column in the table.

expression

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

DEFAULT

Set the column to its default value, which is null if you don't assign a default expression to it.

condition

An expression that returns a value of type BOOLEAN. Update only rows for which this expression returns true.

return_expression

An expression that can include one or more columns from the table. If a column name from the table is specified in return_expression, the value substituted for the column when return_expression is evaluated is determined as follows:

• If the column specified in return_expression is assigned a value in the UPDATE command, then the assigned value is used when evaluating return_expression.

• If the column specified in return_expression isn't assigned a value in the UPDATE command, then the column’s current value in the affected row is used when evaluating return_expression.

record

A record whose field to assign the evaluated return_expression. The first return_expression is assigned to the first field in record, the second return_expression is assigned to the second field in record, and so on. The number of fields in record must exactly match the number of expressions, and the fields must be type-compatible with their assigned expressions.

variable

A variable to which to assign the evaluated return_expression. If more than one return_expression and variable are specified, the first return_expression is assigned to the first variable, the second return_expression is assigned to the second variable, and so on. The number of variables specified following the INTO keyword must exactly match the number of expressions following the RETURNING keyword, and the variables must be type-compatible with their assigned expressions.

collection

A collection in which an element is created from the evaluated return_expression. There can be either:

• A single collection, which can be a collection of a single field or a collection of a record type

• More than one collection, in which case each collection must consist of a single field

  The number of return expressions must match in number and order the number of fields in all specified collections. Each corresponding return_expression and collection field must be type-compatible.

Examples

Change the location to AUSTIN for department 20 in the dept table:

UPDATE dept SET loc = 'AUSTIN' WHERE deptno = 20;

For all employees with job = SALESMAN in the emp table, update the salary by 10%, and increase the commission by 500:

UPDATE emp SET sal = sal * 1.1, comm = comm + 500 WHERE job = 'SALESMAN';

SET ROW example:

CREATE TABLE db1425_t1(a INT, b INT);
INSERT INTO db1425_t1 VALUES(1,2);

DECLARE   
	TYPE rec IS RECORD (x INT, y INT);
    	rec_var rec;    
BEGIN    
	rec_var = row(1000, 1000);
	UPDATE db1425_t1 SET ROW=rec_var WHERE a = 1;   
END;

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