SQL Server involves null operations

NullIt is a very special and annoying value. The calculation result of any value and null is null, which often leads to statement errors. Therefore, when designing the database table structureDefaultTo avoid null. However, this will increase the volume of data files and waste resources. This waste is amazing when the values in the table are very sparse.

Determines whether it is equal to null. Values = NULL and <> null cannot be used.Is nullAndIsNotNull.

Set the field value to null. You can useUpdate XX set YY = NULL. Do not quote null outside.

Insert a new recordInsert XXX (yyy) values (null). Do not quote null outside.

Note the differences between null and "null" and "null.In the SQL Server Query analyzer, the display of null and "null" is exactly the same, which is very confusing.!