1UPDATE(7)                PostgreSQL 13.4 Documentation               UPDATE(7)
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NAME

6       UPDATE - update rows of a table
7

SYNOPSIS

9       [ WITH [ RECURSIVE ] with_query [, ...] ]
10       UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ]
11           SET { column_name = { expression | DEFAULT } |
12                 ( column_name [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) |
13                 ( column_name [, ...] ) = ( sub-SELECT )
14               } [, ...]
15           [ FROM from_item [, ...] ]
16           [ WHERE condition | WHERE CURRENT OF cursor_name ]
17           [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]
18

DESCRIPTION

20       UPDATE changes the values of the specified columns in all rows that
21       satisfy the condition. Only the columns to be modified need be
22       mentioned in the SET clause; columns not explicitly modified retain
23       their previous values.
24
25       There are two ways to modify a table using information contained in
26       other tables in the database: using sub-selects, or specifying
27       additional tables in the FROM clause. Which technique is more
28       appropriate depends on the specific circumstances.
29
30       The optional RETURNING clause causes UPDATE to compute and return
31       value(s) based on each row actually updated. Any expression using the
32       table's columns, and/or columns of other tables mentioned in FROM, can
33       be computed. The new (post-update) values of the table's columns are
34       used. The syntax of the RETURNING list is identical to that of the
35       output list of SELECT.
36
37       You must have the UPDATE privilege on the table, or at least on the
38       column(s) that are listed to be updated. You must also have the SELECT
39       privilege on any column whose values are read in the expressions or
40       condition.
41

PARAMETERS

43       with_query
44           The WITH clause allows you to specify one or more subqueries that
45           can be referenced by name in the UPDATE query. See Section 7.8 and
46           SELECT(7) for details.
47
48       table_name
49           The name (optionally schema-qualified) of the table to update. If
50           ONLY is specified before the table name, matching rows are updated
51           in the named table only. If ONLY is not specified, matching rows
52           are also updated in any tables inheriting from the named table.
53           Optionally, * can be specified after the table name to explicitly
54           indicate that descendant tables are included.
55
56       alias
57           A substitute name for the target table. When an alias is provided,
58           it completely hides the actual name of the table. For example,
59           given UPDATE foo AS f, the remainder of the UPDATE statement must
60           refer to this table as f not foo.
61
62       column_name
63           The name of a column in the table named by table_name. The column
64           name can be qualified with a subfield name or array subscript, if
65           needed. Do not include the table's name in the specification of a
66           target column — for example, UPDATE table_name SET table_name.col =
67           1 is invalid.
68
69       expression
70           An expression to assign to the column. The expression can use the
71           old values of this and other columns in the table.
72
73       DEFAULT
74           Set the column to its default value (which will be NULL if no
75           specific default expression has been assigned to it). An identity
76           column will be set to a new value generated by the associated
77           sequence. For a generated column, specifying this is permitted but
78           merely specifies the normal behavior of computing the column from
79           its generation expression.
80
81       sub-SELECT
82           A SELECT sub-query that produces as many output columns as are
83           listed in the parenthesized column list preceding it. The sub-query
84           must yield no more than one row when executed. If it yields one
85           row, its column values are assigned to the target columns; if it
86           yields no rows, NULL values are assigned to the target columns. The
87           sub-query can refer to old values of the current row of the table
88           being updated.
89
90       from_item
91           A table expression allowing columns from other tables to appear in
92           the WHERE condition and update expressions. This uses the same
93           syntax as the FROM clause of a SELECT statement; for example, an
94           alias for the table name can be specified. Do not repeat the target
95           table as a from_item unless you intend a self-join (in which case
96           it must appear with an alias in the from_item).
97
98       condition
99           An expression that returns a value of type boolean. Only rows for
100           which this expression returns true will be updated.
101
102       cursor_name
103           The name of the cursor to use in a WHERE CURRENT OF condition. The
104           row to be updated is the one most recently fetched from this
105           cursor. The cursor must be a non-grouping query on the UPDATE's
106           target table. Note that WHERE CURRENT OF cannot be specified
107           together with a Boolean condition. See DECLARE(7) for more
108           information about using cursors with WHERE CURRENT OF.
109
110       output_expression
111           An expression to be computed and returned by the UPDATE command
112           after each row is updated. The expression can use any column names
113           of the table named by table_name or table(s) listed in FROM. Write
114           * to return all columns.
115
116       output_name
117           A name to use for a returned column.
118

OUTPUTS

120       On successful completion, an UPDATE command returns a command tag of
121       the form
122
123           UPDATE count
124
125       The count is the number of rows updated, including matched rows whose
126       values did not change. Note that the number may be less than the number
127       of rows that matched the condition when updates were suppressed by a
128       BEFORE UPDATE trigger. If count is 0, no rows were updated by the query
129       (this is not considered an error).
130
131       If the UPDATE command contains a RETURNING clause, the result will be
132       similar to that of a SELECT statement containing the columns and values
133       defined in the RETURNING list, computed over the row(s) updated by the
134       command.
135

NOTES

137       When a FROM clause is present, what essentially happens is that the
138       target table is joined to the tables mentioned in the from_item list,
139       and each output row of the join represents an update operation for the
140       target table. When using FROM you should ensure that the join produces
141       at most one output row for each row to be modified. In other words, a
142       target row shouldn't join to more than one row from the other table(s).
143       If it does, then only one of the join rows will be used to update the
144       target row, but which one will be used is not readily predictable.
145
146       Because of this indeterminacy, referencing other tables only within
147       sub-selects is safer, though often harder to read and slower than using
148       a join.
149
150       In the case of a partitioned table, updating a row might cause it to no
151       longer satisfy the partition constraint of the containing partition. In
152       that case, if there is some other partition in the partition tree for
153       which this row satisfies its partition constraint, then the row is
154       moved to that partition. If there is no such partition, an error will
155       occur. Behind the scenes, the row movement is actually a DELETE and
156       INSERT operation.
157
158       There is a possibility that a concurrent UPDATE or DELETE on the row
159       being moved will get a serialization failure error. Suppose session 1
160       is performing an UPDATE on a partition key, and meanwhile a concurrent
161       session 2 for which this row is visible performs an UPDATE or DELETE
162       operation on this row. In such case, session 2's UPDATE or DELETE will
163       detect the row movement and raise a serialization failure error (which
164       always returns with an SQLSTATE code '40001'). Applications may wish to
165       retry the transaction if this occurs. In the usual case where the table
166       is not partitioned, or where there is no row movement, session 2 would
167       have identified the newly updated row and carried out the UPDATE/DELETE
168       on this new row version.
169
170       Note that while rows can be moved from local partitions to a
171       foreign-table partition (provided the foreign data wrapper supports
172       tuple routing), they cannot be moved from a foreign-table partition to
173       another partition.
174

EXAMPLES

176       Change the word Drama to Dramatic in the column kind of the table
177       films:
178
179           UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
180
181       Adjust temperature entries and reset precipitation to its default value
182       in one row of the table weather:
183
184           UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
185             WHERE city = 'San Francisco' AND date = '2003-07-03';
186
187       Perform the same operation and return the updated entries:
188
189           UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
190             WHERE city = 'San Francisco' AND date = '2003-07-03'
191             RETURNING temp_lo, temp_hi, prcp;
192
193       Use the alternative column-list syntax to do the same update:
194
195           UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
196             WHERE city = 'San Francisco' AND date = '2003-07-03';
197
198       Increment the sales count of the salesperson who manages the account
199       for Acme Corporation, using the FROM clause syntax:
200
201           UPDATE employees SET sales_count = sales_count + 1 FROM accounts
202             WHERE accounts.name = 'Acme Corporation'
203             AND employees.id = accounts.sales_person;
204
205       Perform the same operation, using a sub-select in the WHERE clause:
206
207           UPDATE employees SET sales_count = sales_count + 1 WHERE id =
208             (SELECT sales_person FROM accounts WHERE name = 'Acme Corporation');
209
210       Update contact names in an accounts table to match the currently
211       assigned salesmen:
212
213           UPDATE accounts SET (contact_first_name, contact_last_name) =
214               (SELECT first_name, last_name FROM salesmen
215                WHERE salesmen.id = accounts.sales_id);
216
217       A similar result could be accomplished with a join:
218
219           UPDATE accounts SET contact_first_name = first_name,
220                               contact_last_name = last_name
221             FROM salesmen WHERE salesmen.id = accounts.sales_id;
222
223       However, the second query may give unexpected results if salesmen.id is
224       not a unique key, whereas the first query is guaranteed to raise an
225       error if there are multiple id matches. Also, if there is no match for
226       a particular accounts.sales_id entry, the first query will set the
227       corresponding name fields to NULL, whereas the second query will not
228       update that row at all.
229
230       Update statistics in a summary table to match the current data:
231
232           UPDATE summary s SET (sum_x, sum_y, avg_x, avg_y) =
233               (SELECT sum(x), sum(y), avg(x), avg(y) FROM data d
234                WHERE d.group_id = s.group_id);
235
236       Attempt to insert a new stock item along with the quantity of stock. If
237       the item already exists, instead update the stock count of the existing
238       item. To do this without failing the entire transaction, use
239       savepoints:
240
241           BEGIN;
242           -- other operations
243           SAVEPOINT sp1;
244           INSERT INTO wines VALUES('Chateau Lafite 2003', '24');
245           -- Assume the above fails because of a unique key violation,
246           -- so now we issue these commands:
247           ROLLBACK TO sp1;
248           UPDATE wines SET stock = stock + 24 WHERE winename = 'Chateau Lafite 2003';
249           -- continue with other operations, and eventually
250           COMMIT;
251
252       Change the kind column of the table films in the row on which the
253       cursor c_films is currently positioned:
254
255           UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;
256

COMPATIBILITY

258       This command conforms to the SQL standard, except that the FROM and
259       RETURNING clauses are PostgreSQL extensions, as is the ability to use
260       WITH with UPDATE.
261
262       Some other database systems offer a FROM option in which the target
263       table is supposed to be listed again within FROM. That is not how
264       PostgreSQL interprets FROM. Be careful when porting applications that
265       use this extension.
266
267       According to the standard, the source value for a parenthesized
268       sub-list of target column names can be any row-valued expression
269       yielding the correct number of columns.  PostgreSQL only allows the
270       source value to be a row constructor or a sub-SELECT. An individual
271       column's updated value can be specified as DEFAULT in the
272       row-constructor case, but not inside a sub-SELECT.
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276PostgreSQL 13.4                      2021                            UPDATE(7)
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