Database Access Commands › Logical Record Facility Commands › WHERE Clause

WHERE Clause

A WHERE clause is used to specify criteria for selection of one or more occurrences of a logical record that is the object of an ERASE, MODIFY, OBTAIN, or STORE command. A WHERE clause is also used to direct LRF to a particular logical record path.

Considerations

• A WHERE clause is specified in the form of an expression that consists of one or more conditions to be tested.
  • Multiple conditions are combined with the logical operators AND and OR.
  • The logical operator NOT can precede a single condition or a compound condition that is enclosed in parentheses. NOT specifies the opposite of the condition.
• A test condition is expressed as a comparison or a keyword.
• A logical record occurrence is selected only if the entire expression evaluates as true.
• Operators in a conditional expression are evaluated one at a time, from left to right, in order of precedence.

  Note:The default order of precedence is the same as that described for other conditional expressions discussed in Conditional Expressions.