Operators

Type

Concept

Purpose

Operators are used to manipulate variables and to tell DataEase how to carry out certain Processing and Control Procedures (such as in what order to process records, what statistics to generate, etc.). DQL includes seven types of operators:

• Comparison Operators are used to compare two values and process a record depending on the result of the comparison. Examples include <= (less than or equal to), < (less than), = (equal to), > (greater than), >= (greater than or equal to), between, and not.

• Grouping/Sorting Operators tell DataEase how to group and sort records when you process data using the list records command. Examples include in groups, in order, and in reverse.

• Relational Operators all and any are used to list records related to the record currently being processed. all tells DataEase to list all records related to the current record; any tells DataEase to list only the first related record in the database.

• Statistical Operators summarize the values of a specified field for all records processed. Examples include sum, mean, max, min, and std.dev.

• Conditional Statistical Operators summarize statistical information about a specific condition that occurs in a set of records. Examples include count, percent, and item.

• Relational Statistical Operators summarize information about fields in a set of related records. Examples include count of, highest of, lowest of, mean of, and sum of.

• General Operators include the arithmetic operators (*(asterisk) ,/ ,+ (addition) , and - (subtraction) ), the assignment operator (:=) used to assign a value to a field or variable, and the logical operators (and and or ) that let you select records based on multiple criteria, and execute Procedural Commands based on more than one condition.

There is a separate entry for each individual operator in this language reference.