What is QUEL?
QUEL is the original INGRES DML, now supplanted by SQL for commercial reasons. There is a small number of very well regarded authorities, as well as long-time Ingres users who believe that QUEL is superior to SQL. QUEL is available as part of the INGRES base system. The interfaces are `quel’ (a terminal monitor equivalent and similar to `sql’) and `iquel’ (similar to `isql’). Report Writer is able to determine automatically whether SQL or QUEL is used in the .QUERY section. The embedded pre-processor is `eqc’ for C. QUEL is based on the relational calculus; SQL is based on the relational algebra. There are many operations that are straight forward in QUEL that are not readily reproduced in SQL. Although it is de-emphasized, QUEL _IS_ supported and Ingres Corp has not yet announced that it will be dropped.
