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Embedded SQL-92
Guide and Reference
NULL Values in the WHERE Clause
A select operation succeeds if the search condition in the WHERE clause evaluates to TRUE. A row is not selected if the search condition evaluates to FALSE or is unknown.
EXAMPLEIn the following example, if commission is NULL for empno 2004, the search condition is not satisfied:
The search condition with an OR evaluates to TRUE:
You can select or reject a row containing NULL values in a column by using the [NOT] NULL search condition:
EXAMPLE
The following example shows how to select employee names and department numbers for employees who have not been assigned to any project:
You perform a join between two tables using a WHERE clause. Rows do not meet the search criteria if either the salary column in either table is NULL or if the salary columns in both tables are NULL:
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