Changes existing data in a table.
UPDATE
{
table_name WITH ( <table_hint_limited> [...n])
| view_name
| rowset_function_limited
}
SET
{column_name = {expression | DEFAULT | NULL}
| @variable = expression
| @variable = column = expression } [,...n]
{{[FROM {<table_source>} [,...n] ]
[WHERE
<search_condition>] }
|
[WHERE CURRENT OF
{ { [GLOBAL] cursor_name } | cursor_variable_name}
] }
[OPTION (<query_hint> [,...n] )]
<table_source> ::=
table_name [ [AS] table_alias ] [ WITH ( <table_hint> [,...n]) ]
| view_name [ [AS] table_alias ]
| rowset_function [ [AS] table_alias ]
| derived_table [AS] table_alias [ (column_alias [,...n] ) ]
| <joined_table>
<joined_table> ::=
<table_source> <join_type> <table_source> ON <search_condition>
| <table_source> CROSS JOIN <table_source>
| <joined_table>
<join_type> ::=
[ INNER | { { LEFT | RIGHT | FULL } [OUTER] } ]
[ <join_hint> ]
JOIN
<table_hint_limited> ::=
{ INDEX(index_val [,...n])
| FASTFIRSTROW
| HOLDLOCK
| PAGLOCK
| READCOMMITTED
| REPEATABLEREAD
| ROWLOCK
| SERIALIZABLE
| TABLOCK
| TABLOCKX
}
<table_hint> ::=
{ INDEX(index_val [,...n])
| FASTFIRSTROW
| HOLDLOCK
| NOLOCK
| PAGLOCK
| READCOMMITTED
| READPAST
| READUNCOMMITTED
| REPEATABLEREAD
| ROWLOCK
| SERIALIZABLE
| TABLOCK
| TABLOCKX
| UPDLOCK
}
<query_hint> ::=
{ { HASH | ORDER } GROUP
| { CONCAT | HASH | MERGE } UNION
| {LOOP | MERGE | HASH} JOIN
| FAST number_rows
| FORCE ORDER
| MAXDOP
| ROBUST PLAN
| KEEP PLAN
}
If a qualified column name is specified, the qualifier must match the table or view name in the UPDATE clause. For example, this is valid:
UPDATE authors
SET authors.au_fname = 'Annie'
WHERE au_fname = 'Anne'
A table alias specified in a FROM clause cannot be used as a qualifier in SET column_name. For example, this is not valid:
UPDATE titles
SET t.ytd_sales = t.ytd_sales + s.qty
FROM titles t, sales s
WHERE t.title_id = s.title_id
AND s.ord_date = (SELECT MAX(sales.ord_date) FROM sales)
To make the example work, remove the t. alias from the column name.
UPDATE titles
SET ytd_sales = t.ytd_sales + s.qty
FROM titles t, sales s
WHERE t.title_id = s.title_id
AND s.ord_date = (SELECT MAX(sales.ord_date) FROM sales)
SET @variable = column = expression sets the variable to the same value as the column. This differs from SET @variable = column, column = expression, which sets the variable to the pre-update value of the column.
If the table being updated is the same as the table in the FROM clause, and there is only one reference to the table in the FROM clause, table_alias may or may not be specified. If the table being updated appears more than one time in the FROM clause, one (and only one) reference to the table must not specify a table alias. All other references to the table in the FROM clause must include a table alias.
FROM tab1 LEFT OUTER JOIN tab1.c3 = tab2.c3
RIGHT OUTER JOIN tab3 LEFT OUTER JOIN tab4
ON tab3.c1
ON tab2.c3 = tab4.c3
For multiple CROSS joins, use parentheses to change the natural order of the joins.
FROM Suppliers JOIN Products
ON (Suppliers.SupplierID = Products.SupplierID)
When the condition specifies columns, the columns do not have to have the same name or same data type; however, if the data types are not identical, they must be either compatible or types that Microsoft® SQL Server™ can implicitly convert. If the data types cannot be implicitly converted, the condition must explicitly convert the data type using the CAST function.
For more information about search conditions and predicates, see Search Condition.
Note If a join hint is also specified for any particular pair of joined tables in the FROM clause, it takes precedence over any join hint specified in the OPTION clause.
If an update to a row violates a constraint or rule, if it violates the NULL setting for the column, or if the new value is an incompatible data type, the statement is canceled, an error is returned, and no records are updated.
When an UPDATE statement encounters an arithmetic error (overflow, divide by zero, or a domain error) during expression evaluation the update is not performed. The remainder of the batch is not executed, and an error message is returned.
If an update to a column or columns participating in a clustered index causes the size of the clustered index and the row to exceed 8,060 bytes, the update fails and an error message is returned.
If an update query could alter more than one row while updating both the clustering key and one or more text, image, or Unicode columns, the update operation fails and SQL Server returns an error message.
Modifying a text, ntext, or image column with UPDATE initializes the column, assigns a valid text pointer to it, and allocates at least one data page unless updating the column with NULL.
Note The UPDATE statement is logged. If you are replacing or modifying large blocks of text, ntext, or image data, use the WRITETEXT or UPDATETEXT statement instead of the UPDATE statement. The WRITETEXT and UPDATETEXT statements (by default) are not logged.
All char and nchar columns are right-padded to the defined length.
If ANSI_PADDING is set OFF, all trailing spaces are removed from data inserted into varchar and nvarchar columns, except in strings containing only spaces. These strings are truncated to an empty string. If ANSI_PADDING is set ON, trailing spaces are inserted. The Microsoft SQL Server ODBC driver and OLE DB Provider for SQL Server automatically set ANSI_PADDING ON for each connection. This can be configured in ODBC data sources or by setting connection attributes or properties.
A positioned update using a WHERE CURRENT OF clause updates the single row at the current position of the cursor. This can be more accurate than a searched update that uses a WHERE <search_condition> clause to qualify the rows to be updated. A searched update modifies multiple rows when the search condition does not uniquely identify a single row.
The results of an UPDATE statement are undefined if the statement includes a FROM clause that is not specified in such a way that only one value is available for each column occurrence that is updated (in other words, if the UPDATE statement is not deterministic). For example, given the UPDATE statement in the following script, both rows in table s meet the qualifications of the FROM clause in the UPDATE statement, but it is undefined which row from s is used to update the row in table t.
CREATE TABLE s (ColA INT, ColB DECIMAL(10,3))
GO
CREATE TABLE t (ColA INT PRIMARY KEY, ColB DECIMAL(10,3))
GO
INSERT INTO s VALUES(1, 10.0)
INSERT INTO s VALUES(1, 20.0)
INSERT INTO t VALUES(1, 0.0)
GO
UPDATE t
SET t.ColB = t.ColB + s.ColB
FROM t INNER JOIN s ON (t.ColA = s.ColA)
GO
The same problem can occur when combining the FROM and WHERE CURRENT OF clauses. In this example, both rows in table t2 meet the qualifications of the FROM clause in the UPDATE statement. It is undefined which row from t2 is to be used to update the row in table t1.
CREATE TABLE t1(c1 INT PRIMARY KEY, c2 INT)
GO
CREATE TABLE t2(d1 INT PRIMARY KEY, d2 INT)
GO
INSERT INTO t1 VALUES (1, 10)
INSERT INTO t2 VALUES (1, 20)
INSERT INTO t2 VALUES (2, 30)
go
DECLARE abc CURSOR LOCAL FOR
SELECT * FROM t1
OPEN abc
FETCH abc
UPDATE t1 SET c2 = c2 + d2
FROM t2
WHERE CURRENT OF abc
GO
Variable names can be used in UPDATE statements to show the old and new values affected. This should only be used when the UPDATE statement affects a single record; if the UPDATE statement affects multiple records, the variables only contain the values for one of the updated rows.
UPDATE permissions default to members of the sysadmin fixed server role, the db_owner fixed database role, and the table owner, who can transfer permissions to other users. SELECT permissions are also required for the table being updated if the UPDATE statement contains a WHERE clause, or if expression in the SET clause uses a column in the table.
These examples show how all rows can be affected if a WHERE clause is eliminated from an UPDATE statement.
If all the publishing houses in the publishers table move their head offices to Atlanta, Georgia, this example shows how the publishers table can updated.
UPDATE publishers
SET city = 'Atlanta', state = 'GA'
This example changes the names of all the publishers to NULL.
UPDATE publishers
SET pub_name = NULL
You can also use computed values in an update. This example doubles all prices in the titles table.
UPDATE titles
SET price = price * 2
The WHERE clause specifies the rows to update. For example, in the unlikely event that northern California is renamed Pacifica (abbreviated PC) and the people of Oakland vote to change the name of their city to Bay City. This example shows how to update the authors table for all former Oakland residents whose addresses are now out of date.
UPDATE authors
SET state = 'PC', city = 'Bay City'
WHERE state = 'CA' AND city = 'Oakland'
You must write another statement to change the name of the state for residents of other northern California cities.
This example modifies the ytd_sales column in the titles table to reflect the most recent sales recorded in the sales table.
UPDATE titles
SET ytd_sales = titles.ytd_sales + sales.qty
FROM titles, sales
WHERE titles.title_id = sales.title_id
AND sales.ord_date = (SELECT MAX(sales.ord_date) FROM sales)
This example assumes that only one set of sales is recorded for a given title on a given date and that updates are current. If this is not the case (if more than one sale for a given title can be recorded on the same day), the example shown here does not work correctly. It executes without error, but each title is updated with only one sale, regardless of how many sales actually occurred on that day. This is because a single UPDATE statement never updates the same row twice.
In the situation in which more than one sale for a given title can occur on the same day, all the sales for each title must be aggregated together within the UPDATE statement, as shown in this example:
UPDATE titles
SET ytd_sales =
(SELECT SUM(qty)
FROM sales
WHERE sales.title_id = titles.title_id
AND sales.ord_date IN (SELECT MAX(ord_date) FROM sales))
FROM titles, sales
This example updates the state column for the first 10 authors from the authors table.
UPDATE authors
SET state = 'ZZ'
FROM (SELECT TOP 10 * FROM authors ORDER BY au_lname) AS t1
WHERE authors.au_id = t1.au_id
| CREATE INDEX | DELETE |
| CREATE TABLE | INSERT |
| CREATE TRIGGER | SET ROWCOUNT |
| Cursors | Text and Image Functions |