Many SQL implementations feature support for two different 'not equal' comparison operators, usually:

• <>
• !=

4D only supports the ANSI-compliant <> operator. This is the operator that appears in the SQL 92 specification. That is to say, 4D's SQL syntax is based on the SQL 92 specification.

The != operator is from Transact-SQL (T-SQL), which is Microsoft's proprietry SQL language. 4D does not directly support T-SQL, though of course much of the syntax overlaps with SQL 92.