Retrieval Using the OR Operator

When OR is used to connect two or more conditions, the compound condition is true if any condition is true, and the row is then retireved. However, if all of the conditional expressions are false, then the row is not selected.

For example, suppose management is interested in any Product Division department OR any department with a budget of % latex2html id marker 5108 $28,000 or greater. This compound condition can be written as follows:

     DIV = 'PROD'  OR  BUDGET >= 28000
In this case OR is the logical operator used.

Table here illustrates the four possible cases that can occur with the logical operator OR for the example just given.

 

Values for Values for Condition1 Condition2
DIV BUDGET DIV='PROD' BUDGET>=28000 Yields Row Result
1 PROD 32000 True True True Retrieved
2 PROD 27500 True False True Retrieved
3 CORP 28000 False True True Retrieved
4 CORP 10500 False False False Not retrieved

Table: Logical Operator OR

Example: Based on the above, let's develop a list of departments for management review, which are either in the Product Division or which have budgets of $28,000 or greater.

If you enter the statement:

     SELECT  DNAME, DIV, BUDGET
     FROM    DEPARTMENT
     WHERE   DIV = 'PROD' OR BUDGET >= 28000 ;
the result displayed will be:

  DNAME                                DIV     BUDGET
  Corporate Legal Support              CORP    28000
  Research and Development             PROD    27500
  Manufacturing                        PROD    32000
  Customer Support and Service         PROD    11000
  Product Marketing and Sales          PROD    25000
  Strategic Planning and Intelligence  INFO    28500

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