silly documentation question
Mark Collins asked whether JOIN alone means INNER JOIN in 14.10 ANSI syntax and noted the online SQL Syntax manual lacks its Introduction section. Art Kagel confirmed JOIN implies INNER, LEFT or RIGHT imply outer joins, and OUTER JOIN alone implies LEFT OUTER. Mark found the Introduction in an old 11.70 PDF; Daniel Karwatka pointed to the ANSI joins documentation page.
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Looking at the online docs for 14.10 , in the SQL Syntax manual section describing the ANSI-style join syntax, I see that the "INNER" keyword is listed above the main path of the diagram, while the JOIN keyword is on the main path, and options such as LEFT and RIGHT are presented under the main path. Am I correct in assuming that INNER is the default, such that if a programmer specified "JOIN" with no other options, it would be treated as an INNER JOIN? I think I'm correct, but I would like to be able to point programmers to the official text stating that is the case. For those who suggest that I should RTFM before posting such an elementary question, I did. Specifically this section , which states that before trying to use the diagrams, " it is helpful to read the syntax diagram section of the Introduction". The problem is, I cannot find an Introduction. The manual jumps straight into the Overview of SQL Syntax. I would expect the Introduction to precede the Overview. I've looked in the 12.10, 14.10, and 15.0 versions of the manual. Perhaps an update to the documentation is in order? Either include the Introduction section in the online version, or move the syntax diagram section into the Overview? ------------------------------ mark collins ------------------------------
Mark: Yes. JOIN alone implies an INNER JOIN while specifying either LEFT or RIGHT implies LEFT OUTER JOIN or RIGHT OUTER JOIN. OUTER JOIN alone implies a LEFT OUTER JOIN. Art ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------
Art, Thanks for the confirmation. This morning, I found an old PDF copy of the 11.70 documentation, which includes the Introduction section. Hopefully someone will see the need to add that to the online docs for the current versions. Mark ------------------------------ mark collins ------------------------------
You might want to look at the following page That explains the various JOINs. https://www.ibm.com/docs/en/informix-servers/14.10.0?topic=clause-ansi-joins#ids_sqs_1026 Here is the same excerpt from the version 11 manual: ------------------------------ Daniel Karwatka ------------------------------