NE or <> operator

Compares two expressions and returns a TRUE value if they are not equal.

Syntax 

 

expression { NE | <> } expression

expression

A constant, field name, variable name, or expression. The expressions on either side of the NE or must be of the same data type.

Example 

This procedure displays information for all items that appear in the catalog. (The CatPage field is not equal to the Unknown value (?) or 0.)

 

r-ne.p

FOR EACH Item NO-LOCK WHERE Item.CatPage <> ? AND Item.CatPage <> 0:   DISPLAY Item.ItemNum Item.ItemName Item.CatPage     WITH TITLE "Catalog Items" USE-TEXT. END.

Notes 

By default, the AVM uses the collation rules you specify to compare characters and sort records. The collation rules specified with the Collation Table (-cpcoll) startup parameter take precedence over a collation specified for any database the AVM accesses during the session, except when the AVM uses or modifies pre-existing indexes. If you do not specify a collation with the -cpcoll startup parameter, the AVM uses the language collation rules defined for the first database on the command line. If you do not specify a database on the command line, the AVM uses the collation rules with the default name "basic" (which might or might not exist in the convmap.cp file).

If one of the expressions has the Unknown value (?) and the other does not, the result is TRUE. If both have the Unknown value (?), the result is FALSE. For SQL, however, if one or both expressions have the Unknown value (?), then the result is the Unknown value (?).

You can compare character strings with NE. Most character comparisons are case insensitive in ABL. That is, all characters are converted to uppercase prior to comparisons. However, it is possible to define fields and variables as case sensitive (although it is not advised, unless strict ANSI SQL adherence is required). If either expression is a field or variable defined as case sensitive, the comparison is case sensitive and “Smith” does not equal “smith”.

Characters are converted to their sort code values for comparison. Using the default case-sensitive collation table, all uppercase letters sort before all lowercase letters (for example, a is greater than Z, but less than b.) Note also that in character code uppercase A is less than [ , \ , ^ , _, and  ’ , but lowercase a is greater than these.

You cannot compare data of different DATE, DATETIME, and DATETIME-TZ data types to each other using NE. You must first convert different date and datetime data types to the same data type before doing a comparison between them.

You can use NE to compare one BLOB field to another. The AVM performs a byte-by-byte comparison.

You can use NE to compare a LONGCHAR variable to another LONGCHAR or CHARACTER variable. The variable values are converted to -cpinternal for comparison and must convert without error, or the AVM raises a run-time error.

You can use NE to compare a CLOB field only to the Unknown value (?).