UPDATE(7)
π NAME π
okay bestie, this is UPDATE(7) β the PostgreSQL 14.24 documentation page β and the manual name is folded in right here like a cute little bookmark. the command itself?
UPDATE β update rows of a table
πΈ SYNOPSIS πΈ
[ WITH [ RECURSIVE ] with_query [, ...] ]
UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ]
SET { column_name = { expression | DEFAULT } |
( column_name [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) |
( column_name [, ...] ) = ( sub-SELECT )
} [, ...]
[ FROM from_item [, ...] ]
[ WHERE condition | WHERE CURRENT OF cursor_name ]
[ RETURNING { * | output_expression [ [ AS ] output_name ] } [, ...] ]
π DESCRIPTION π
okay so UPDATE does one iconic thing: it changes the values of the specified columns in all rows that satisfy the condition. and the way that itβs lowkey chill is that only the columns you actually name in the SET clause need to be mentioned; columns you donβt explicitly modify keep their previous values. no cap. π
there are two ways to modify a table using information contained in other tables in the database: using sub-selects, or specifying additional tables in the FROM clause. which technique is more appropriate depends on the specific circumstances β vibe check each time, bestie.
the optional RETURNING clause causes UPDATE to compute and return value(s) based on each row actually updated. any expression using the tableβs columns, and/or columns of other tables mentioned in FROM, can be computed. the new (post-update) values of the tableβs columns are used. the syntax of the RETURNING list is identical to that of the output list of SELECT. periodt.
π¨ privilege check, bestie: you must have theUPDATEprivilege on the table, or at least on the column(s) that are listed to be updated. you must also have theSELECTprivilege on any column whose values are read in the expressions or condition. donβt skip this part. π
π PARAMETERS π
with_queryβ theWITHclause allows you to specify one or more subqueries that can be referenced by name in theUPDATEquery. see Section 7.8 andSELECT(7)for details. β¨table_nameβ the name (optionally schema-qualified) of the table to update. ifONLYis specified before the table name, matching rows are updated in the named table only. ifONLYis 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.aliasβ a substitute name for the target table. when an alias is provided, it completely hides the actual name of the table. for example, givenUPDATE foo AS f, the remainder of theUPDATEstatement must refer to this table asfnotfoo. not me forgetting this and debugging for twenty minutes ππcolumn_nameβ the name of a column in the table named bytable_name. the column name can be qualified with a subfield name or array subscript, if needed. do not include the tableβs name in the specification of a target column β for example,UPDATE table_name SET table_name.col = 1is invalid. invalid, bestie! πexpressionβ an expression to assign to the column. the expression can use the old values of this and other columns in the table.DEFAULTβ set the column to its default value (which will beNULLif no specific default expression has been assigned to it). an identity column will be set to a new value generated by the associated sequence. for a generated column, specifying this is permitted but merely specifies the normal behavior of computing the column from its generation expression.sub-SELECTβ aSELECTsub-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,NULLvalues are assigned to the target columns. the sub-query can refer to old values of the current row of the table being updated.from_itemβ a table expression allowing columns from other tables to appear in theWHEREcondition and update expressions. this uses the same syntax as theFROMclause of aSELECTstatement; for example, an alias for the table name can be specified. do not repeat the target table as afrom_itemunless you intend a self-join (in which case it must appear with an alias in thefrom_item).conditionβ an expression that returns a value of typeboolean. only rows for which this expression returns true will be updated. β¨cursor_nameβ the name of the cursor to use in aWHERE CURRENT OFcondition. the row to be updated is the one most recently fetched from this cursor. the cursor must be a non-grouping query on theUPDATEβs target table. note thatWHERE CURRENT OFcannot be specified together with a Boolean condition. seeDECLARE(7)for more information about using cursors withWHERE CURRENT OF. π¦output_expressionβ an expression to be computed and returned by theUPDATEcommand after each row is updated. the expression can use any column names of the table named bytable_nameor table(s) listed inFROM. write*to return all columns.output_nameβ a name to use for a returned column.
β OUTPUTS β
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). slay, zero rows is still valid. π
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.
π¦ NOTES π¦
when a FROM clause is present, what essentially happens is that the target table is joined to the tables mentioned in the from_item list, and each output row of the join represents an update operation for the target table. when using FROM you should ensure that the join produces at most one output row for each row to be modified. in other words, a target row shouldnβt join to more than one row from the other table(s). if it does, then only one of the join rows will be used to update the target row, but which one will be used is not readily predictable. π¬
because of this indeterminacy, referencing other tables only within sub-selects is safer, though often harder to read and slower than using a join.
in the case of a partitioned table, updating a row might cause it to no longer satisfy the partition constraint of the containing partition. in that case, if there is some other partition in the partition tree for which this row satisfies its partition constraint, then the row is moved to that partition. if there is no such partition, an error will occur. behind the scenes, the row movement is actually a DELETE and INSERT operation. π§
there is a possibility that a concurrent UPDATE or DELETE on the row being moved will get a serialization failure error. suppose session 1 is performing an UPDATE on a partition key, and meanwhile a concurrent session 2 for which this row is visible performs an UPDATE or DELETE operation on this row. in such case, session 2βs UPDATE or DELETE will detect the row movement and raise a serialization failure error (which always returns with an SQLSTATE code '40001'). applications may wish to retry the transaction if this occurs. in the usual case where the table is not partitioned, or where there is no row movement, session 2 would have identified the newly updated row and carried out the UPDATE/DELETE on this new row version.
note that while rows can be moved from local partitions to a foreign-table partition (provided the foreign data wrapper supports tuple routing), they cannot be moved from a foreign-table partition to another partition. π
π¬ EXAMPLES
Okay bestie, this is the fun part β we're gonna look at it β¨
Example the first: you wanna rename the vibe. Changing the word Drama to Dramatic in the column kind of the table films:
UPDATE films SET kind = 'Dramatic' WHERE kind = 'Drama';
Next up: tweaking those temperature entries and resetting precipitation back to its default value, all 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';
Same thing, but make it give β do the exact same operation and hand the updated entries back to you:
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;
The alternative column-list syntax doing the very same update (same energy, different font π ):
UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
WHERE city = 'San Francisco' AND date = '2003-07-03';
Bump 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;
Same operation, sub-select flavor β this time 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');
Syncing the contact names in an accounts table so they 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 totally 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;
β οΈ But hold on, bestie, listen. The second query may give you unexpected results ifsalesmen.idis not a unique key β whereas the first query is guaranteed to raise an error if there are multipleidmatches. Also, if there's no match for a particularaccounts.sales_identry, the first query will set the corresponding name fields toNULL, whereas the second query will not update that row at all. Different behavior, fr fr π
Updating statistics in a summary table so they 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);
The classic "insert or update" move π₯ β 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;
Last one, cursor girlies rise πΈ β 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;
π COMPATIBILITY
This command conforms to the SQL standard β except that the FROM and RETURNING clauses are PostgreSQL extensions, and so is the ability to use WITH with UPDATE. So like, iconically extra, but in a standard-compliant way π«Ά
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. So bestie, be careful when porting applications that use this extension β no cap, this is a real footgun π
According to the standard, the source value for a parenthesized sub-list of target column names can be any row-valued expression yielding the correct number of columns. PostgreSQL only allows the source value to be 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. That's just how it is, periodt π
And that's the whole page, bestie! β¨ Go update something responsibly. π¦
This absolute queen of a page comes straight from PostgreSQL 14.24, dated 2026, and it's the UPDATE(7) manual β drink water, back up your data, and slay π
π¦ where this page comes from
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- π girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on : a language model's rewrite of the original, under its terms