Sql lock table while updating
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.Common table expressions can also be used with the SELECT, INSERT, DELETE, and CREATE VIEW statements.For more information, see WITH common_table_expression (Transact-SQL). For information about table hints, see Table Hints (Transact-SQL).
For example, in the UPDATE statement in the following script, both rows in USE Adventure Works2012; GO IF OBJECT_ID ('dbo. To replace or modify large blocks of text, ntext, or image data, use WRITETEXT or UPDATETEXT instead of the UPDATE statement.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.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.
For example, a partial update of a varchar(max) column might delete or modify only the first 200 characters of the column, whereas a full update would delete or modify all the data in the column. WRITE updates that insert or append new data are minimally logged if the database recovery model is set to bulk-logged or simple.