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UPDATE(7)               PostgreSQL 9.5.0 Documentation               UPDATE(7)


UPDATE - update rows of a table


[ WITH [ RECURSIVE ] with_query [, ...] ] UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ] SET { column_name = { expression | DEFAULT } | ( column_name [, ...] ) = ( { expression | DEFAULT } [, ...] ) | ( column_name [, ...] ) = ( sub-SELECT ) } [, ...] [ FROM from_list ] [ WHERE condition | WHERE CURRENT OF cursor_name ] [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]




with_query The WITH clause allows you to specify one or more subqueries that can be referenced by name in the UPDATE query. See Section 7.8, "WITH Queries (Common Table Expressions)", in the documentation and SELECT(7) for details. table_name The name (optionally schema-qualified) of the table to update. If ONLY is specified before the table name, matching rows are updated in the named table only. If ONLY is not specified, matching rows are also updated in any tables inheriting from the named table. Optionally, * can be specified after the table name to explicitly indicate that descendant tables are included. alias A substitute name for the target table. When an alias is provided, it completely hides the actual name of the table. For example, given UPDATE foo AS f, the remainder of the UPDATE statement must refer to this table as f not foo. column_name The name of a column in the table named by table_name. The column name can be qualified with a subfield name or array subscript, if needed. Do not include the table's name in the specification of a target column -- for example, UPDATE tab SET tab.col = 1 is invalid. 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 will be NULL if no specific default expression has been assigned to it). sub-SELECT A SELECT sub-query that produces as many output columns as are listed in the parenthesized column list preceding it. The sub-query must yield no more than one row when executed. If it yields one row, its column values are assigned to the target columns; if it yields no rows, NULL values are assigned to the target columns. The sub-query can refer to old values of the current row of the table being updated. from_list A list of table expressions, allowing columns from other tables to appear in the WHERE condition and the update expressions. This is similar to the list of tables that can be specified in the FROM Clause of a SELECT statement. Note that the target table must not appear in the from_list, unless you intend a self-join (in which case it must appear with an alias in the from_list). condition An expression that returns a value of type boolean. Only rows for which this expression returns true will be updated. cursor_name The name of the cursor to use in a WHERE CURRENT OF condition. The row to be updated is the one most recently fetched from this cursor. The cursor must be a non-grouping query on the UPDATE's target table. Note that WHERE CURRENT OF cannot be specified together with a Boolean condition. See DECLARE(7) for more information about using cursors with WHERE CURRENT OF. output_expression An expression to be computed and returned by the UPDATE command after each row is updated. The expression can use any column names of the table named by table_name or table(s) listed in FROM. Write * to return all columns. output_name A name to use for a returned column.


On successful completion, an UPDATE command returns a command tag of the form UPDATE count The count is the number of rows updated, including matched rows whose values did not change. Note that the number may be less than the number of rows that matched the condition when updates were suppressed by a BEFORE UPDATE trigger. If count is 0, no rows were updated by the query (this is not considered an error). If the UPDATE command contains a RETURNING clause, the result will be similar to that of a SELECT statement containing the columns and values defined in the RETURNING list, computed over the row(s) updated by the command.




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'; Perform the same operation and return the updated entries: UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT WHERE city = 'San Francisco' AND date = '2003-07-03' RETURNING temp_lo, temp_hi, prcp; Use the alternative column-list syntax to do the same update: UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT) WHERE city = 'San Francisco' AND date = '2003-07-03'; Increment the sales count of the salesperson who manages the account for Acme Corporation, using the FROM clause syntax: UPDATE employees SET sales_count = sales_count + 1 FROM accounts WHERE accounts.name = 'Acme Corporation' AND employees.id = accounts.sales_person; Perform the same operation, using a sub-select in the WHERE clause: UPDATE employees SET sales_count = sales_count + 1 WHERE id = (SELECT sales_person FROM accounts WHERE name = 'Acme Corporation'); Update contact names in an accounts table to match the currently assigned salesmen: UPDATE accounts SET (contact_first_name, contact_last_name) = (SELECT first_name, last_name FROM salesmen WHERE salesmen.id = accounts.sales_id); A similar result could be accomplished with a join: UPDATE accounts SET contact_first_name = first_name, contact_last_name = last_name FROM salesmen WHERE salesmen.id = accounts.sales_id; However, the second query may give unexpected results if salesmen.id is not a unique key, whereas the first query is guaranteed to raise an error if there are multiple id matches. Also, if there is no match for a particular accounts.sales_id entry, the first query will set the corresponding name fields to NULL, whereas the second query will not update that row at all. Update statistics in a summary table to match the current data: UPDATE summary s SET (sum_x, sum_y, avg_x, avg_y) = (SELECT sum(x), sum(y), avg(x), avg(y) FROM data d WHERE d.group_id = s.group_id); Attempt to insert a new stock item along with the quantity of stock. If the item already exists, instead update the stock count of the existing item. To do this without failing the entire transaction, use savepoints: BEGIN; -- other operations SAVEPOINT sp1; INSERT INTO wines VALUES('Chateau Lafite 2003', '24'); -- Assume the above fails because of a unique key violation, -- so now we issue these commands: ROLLBACK TO sp1; UPDATE wines SET stock = stock + 24 WHERE winename = 'Chateau Lafite 2003'; -- continue with other operations, and eventually COMMIT; Change the kind column of the table films in the row on which the cursor c_films is currently positioned: UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;


This command conforms to the SQL standard, except that the FROM and RETURNING clauses are PostgreSQL extensions, as is the ability to use WITH with UPDATE. Some other database systems offer a FROM option in which the target table is supposed to be listed again within FROM. That is not how PostgreSQL interprets FROM. Be careful when porting applications that use this extension. According to the standard, the source value for a parenthesized sub-list of column names can be any row-valued expression yielding the correct number of columns. PostgreSQL only allows the source value to be a parenthesized list of expressions (a row constructor) or a sub-SELECT. An individual column's updated value can be specified as DEFAULT in the row-constructor case, but not inside a sub-SELECT. PostgreSQL 9.5.0 2016 UPDATE(7)

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