Sql updating table from same table
If the UPDATE statement affects multiple records, to return the old and new values for each record, use the OUTPUT clause. This can be configured in ODBC data sources or by setting connection attributes or properties.
Use caution when specifying the FROM clause to provide the criteria for the update operation. For more information, see SET ANSI_PADDING (Transact-SQL).
For more information, see The Transaction Log (SQL Server).
The Database Engine converts a partial update to a full update when the UPDATE statement causes either of these actions: are specified in bytes for varbinary and varchar data types and in characters for the nvarchar data type.
Table1', ' U') IS NOT NULL DROP TABLE dbo. Table2', ' U') IS NOT NULL DROP TABLE dbo. Table1 (Col A int NOT NULL, Col B decimal(10,3) NOT NULL); GO CREATE TABLE dbo. If the UPDATE statement could change more than one row while updating both the clustering key and one or more text, ntext, or image columns, the partial update to these columns is executed as a full replacement of the values.
Table2 (Col A int PRIMARY KEY NOT NULL, Col B decimal(10,3) NOT NULL); GO INSERT INTO dbo. Important The ntext, text, and image data types will be removed in a future version of Microsoft SQL Server.
Use the @@ROWCOUNT function to return the number of inserted rows to the client application. If ANSI_PADDING is set to OFF, all trailing spaces are removed from data inserted into varchar and nvarchar columns, except in strings that contain only spaces. If ANSI_PADDING is set to ON, trailing spaces are inserted.
For more information, see @@ROWCOUNT (Transact-SQL). Variable names can be used in UPDATE statements to show the old and new values affected, but this should be used only when the UPDATE statement affects a single record. The Microsoft SQL Server ODBC driver and OLE DB Provider for SQL Server automatically set ANSI_PADDING ON for each connection.
If ' N' is not specified, SQL Server converts the string to the code page that corresponds to the default collation of the database or column.This can be more accurate than a searched update that uses a WHERE ] ) Specifies that optimizer hints are used to customize the way the Database Engine processes the statement. Avoid using these hints in this context in new development work, and plan to modify applications that currently use them.For more information, see Query Hints (Transact-SQL). All char and nchar columns are right-padded to the defined length.CURRENT OF Specifies that the update is performed at the current position of the specified cursor. Table1', ' U') IS NOT NULL DROP TABLE dbo. Table2', ' U') IS NOT NULL DROP TABLE dbo. Table1 (c1 int PRIMARY KEY NOT NULL, c2 int NOT NULL); GO CREATE TABLE dbo. Table2 WHERE CURRENT OF abc; GO SELECT c1, c2 FROM dbo.A positioned update using a WHERE CURRENT OF clause updates the single row at the current position of the cursor. Table2 (d1 int PRIMARY KEY NOT NULL, d2 int NOT NULL); GO INSERT INTO dbo. Table2 VALUES (1, 20), (2, 30); GO DECLARE abc CURSOR LOCAL FOR SELECT c1, c2 FROM dbo. Table1; GO Support for use of the READUNCOMMITTED and NOLOCK hints in the FROM clause that apply to the target table of an UPDATE or DELETE statement will be removed in a future version of SQL Server.