1UPDATE(7)                PostgreSQL 12.6 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).
76
77       sub-SELECT
78           A SELECT sub-query that produces as many output columns as are
79           listed in the parenthesized column list preceding it. The sub-query
80           must yield no more than one row when executed. If it yields one
81           row, its column values are assigned to the target columns; if it
82           yields no rows, NULL values are assigned to the target columns. The
83           sub-query can refer to old values of the current row of the table
84           being updated.
85
86       from_item
87           A table expression allowing columns from other tables to appear in
88           the WHERE condition and update expressions. This uses the same
89           syntax as the FROM Clause of a SELECT statement; for example, an
90           alias for the table name can be specified. Do not repeat the target
91           table as a from_item unless you intend a self-join (in which case
92           it must appear with an alias in the from_item).
93
94       condition
95           An expression that returns a value of type boolean. Only rows for
96           which this expression returns true will be updated.
97
98       cursor_name
99           The name of the cursor to use in a WHERE CURRENT OF condition. The
100           row to be updated is the one most recently fetched from this
101           cursor. The cursor must be a non-grouping query on the UPDATE's
102           target table. Note that WHERE CURRENT OF cannot be specified
103           together with a Boolean condition. See DECLARE(7) for more
104           information about using cursors with WHERE CURRENT OF.
105
106       output_expression
107           An expression to be computed and returned by the UPDATE command
108           after each row is updated. The expression can use any column names
109           of the table named by table_name or table(s) listed in FROM. Write
110           * to return all columns.
111
112       output_name
113           A name to use for a returned column.
114

OUTPUTS

116       On successful completion, an UPDATE command returns a command tag of
117       the form
118
119           UPDATE count
120
121       The count is the number of rows updated, including matched rows whose
122       values did not change. Note that the number may be less than the number
123       of rows that matched the condition when updates were suppressed by a
124       BEFORE UPDATE trigger. If count is 0, no rows were updated by the query
125       (this is not considered an error).
126
127       If the UPDATE command contains a RETURNING clause, the result will be
128       similar to that of a SELECT statement containing the columns and values
129       defined in the RETURNING list, computed over the row(s) updated by the
130       command.
131

NOTES

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

EXAMPLES

172       Change the word Drama to Dramatic in the column kind of the table
173       films:
174
175           UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
176
177       Adjust temperature entries and reset precipitation to its default value
178       in one row of the table weather:
179
180           UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
181             WHERE city = 'San Francisco' AND date = '2003-07-03';
182
183       Perform the same operation and return the updated entries:
184
185           UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
186             WHERE city = 'San Francisco' AND date = '2003-07-03'
187             RETURNING temp_lo, temp_hi, prcp;
188
189       Use the alternative column-list syntax to do the same update:
190
191           UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
192             WHERE city = 'San Francisco' AND date = '2003-07-03';
193
194       Increment the sales count of the salesperson who manages the account
195       for Acme Corporation, using the FROM clause syntax:
196
197           UPDATE employees SET sales_count = sales_count + 1 FROM accounts
198             WHERE accounts.name = 'Acme Corporation'
199             AND employees.id = accounts.sales_person;
200
201       Perform the same operation, using a sub-select in the WHERE clause:
202
203           UPDATE employees SET sales_count = sales_count + 1 WHERE id =
204             (SELECT sales_person FROM accounts WHERE name = 'Acme Corporation');
205
206       Update contact names in an accounts table to match the currently
207       assigned salesmen:
208
209           UPDATE accounts SET (contact_first_name, contact_last_name) =
210               (SELECT first_name, last_name FROM salesmen
211                WHERE salesmen.id = accounts.sales_id);
212
213       A similar result could be accomplished with a join:
214
215           UPDATE accounts SET contact_first_name = first_name,
216                               contact_last_name = last_name
217             FROM salesmen WHERE salesmen.id = accounts.sales_id;
218
219       However, the second query may give unexpected results if salesmen.id is
220       not a unique key, whereas the first query is guaranteed to raise an
221       error if there are multiple id matches. Also, if there is no match for
222       a particular accounts.sales_id entry, the first query will set the
223       corresponding name fields to NULL, whereas the second query will not
224       update that row at all.
225
226       Update statistics in a summary table to match the current data:
227
228           UPDATE summary s SET (sum_x, sum_y, avg_x, avg_y) =
229               (SELECT sum(x), sum(y), avg(x), avg(y) FROM data d
230                WHERE d.group_id = s.group_id);
231
232       Attempt to insert a new stock item along with the quantity of stock. If
233       the item already exists, instead update the stock count of the existing
234       item. To do this without failing the entire transaction, use
235       savepoints:
236
237           BEGIN;
238           -- other operations
239           SAVEPOINT sp1;
240           INSERT INTO wines VALUES('Chateau Lafite 2003', '24');
241           -- Assume the above fails because of a unique key violation,
242           -- so now we issue these commands:
243           ROLLBACK TO sp1;
244           UPDATE wines SET stock = stock + 24 WHERE winename = 'Chateau Lafite 2003';
245           -- continue with other operations, and eventually
246           COMMIT;
247
248       Change the kind column of the table films in the row on which the
249       cursor c_films is currently positioned:
250
251           UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;
252

COMPATIBILITY

254       This command conforms to the SQL standard, except that the FROM and
255       RETURNING clauses are PostgreSQL extensions, as is the ability to use
256       WITH with UPDATE.
257
258       Some other database systems offer a FROM option in which the target
259       table is supposed to be listed again within FROM. That is not how
260       PostgreSQL interprets FROM. Be careful when porting applications that
261       use this extension.
262
263       According to the standard, the source value for a parenthesized
264       sub-list of target column names can be any row-valued expression
265       yielding the correct number of columns.  PostgreSQL only allows the
266       source value to be a row constructor or a sub-SELECT. An individual
267       column's updated value can be specified as DEFAULT in the
268       row-constructor case, but not inside a sub-SELECT.
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272PostgreSQL 12.6                      2021                            UPDATE(7)
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