This can also be used to change the column to NULL if the column has no default and is defined to allow null values.
Compound assignment operator: = Add and assign -= Subtract and assign *= Multiply and assign /= Divide and assign %= Modulo and assign &= Bitwise AND and assign ^= Bitwise XOR and assign |= Bitwise OR and assign Returns updated data or expressions based on it as part of the UPDATE operation.
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, that is if the UPDATE statement is not deterministic. 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 the column is being updated with NULL.
FROM Specifies that a table, view, or derived table source is used to provide the criteria for the update operation. If the object being updated is the same as the object in the FROM clause and there is only one reference to the object in the FROM clause, an object alias may or may not be specified.
If the object being updated appears more than one time in the FROM clause, one, and only one, reference to the object must not specify a table alias.
If you omit the WHERE clause, all records in the table will be updated!
The WHERE clause specifies which record(s) that should be updated.
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.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).Any characters not found in this code page are lost.DEFAULT Specifies that the default value defined for the column is to replace the existing value in the column.Note Any call to OPENDATASOURCE, OPENQUERY, or OPENROWSET in the FROM clause is evaluated separately and independently from any call to these functions used as the target of the update, even if identical arguments are supplied to the two calls.