Updating columns in sql
Specifying DEFAULT for the update value sets the value of the column to the default defined for that table.The DEFAULT literal is the only value which you can directly assign to a generated column.A searched update statement depends on the table being updated, all of its conglomerates (units of storage such as heaps or indexes), all of its constraints, and any other table named in the WHERE clause or SET expressions.A CREATE or DROP INDEX statement or an ALTER TABLE statement for the target table of a prepared searched update statement invalidates the prepared searched update statement.If columns were specified in the FOR UPDATE clause of the SELECT statement used to generate the cursor, only those columns can be updated.If no columns were specified or the select statement did not include a FOR UPDATE clause, all columns may be updated.The first syntactical form, called a searched update, updates the value of one or more columns for all rows of the table for which the WHERE clause evaluates to TRUE.The second syntactical form, called a positioned update, updates one or more columns on the current row of an open, updatable cursor.
A view with an INSTEAD OF UPDATE trigger cannot be a target of an UPDATE with a FROM clause. 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.
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The SQL Server (Transact-SQL) UPDATE statement is used to update existing records in a table in a SQL Server database.
There are 3 syntaxes for the UPDATE statement depending on whether you are performing a traditional update or updating one table with data from another table.