SQL Small Summary 2

SQL NULL Value

If a column in the table is optional, we can insert a new record or update an existing record without adding a value to the column. This means that the field will be saved with a NULL value.

NULL values are handled differently than other values.

NULL is used as a placeholder for unknown or non-applicable values.

Note: Cannot compare NULL and 0; they are not equivalent.

You cannot use a comparison operator to test for NULL values, such as =, <, or <>.

SQL Small Summary 2