Updating table with values from another table
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.Specifies the condition to be met for the rows to be updated.The search condition can also be the condition upon which a join is based.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.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).
When I try to update only the missing data the non-matched data is also updated but to NULL. The reason some of your rows are getting NULLs updated is due to the subquery.The OUTPUT clause is not supported in any DML statements that target remote tables or views.For more information, see OUTPUT Clause (Transact-SQL).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).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.