While editing, building up, or cherry picking from SQL statements I can find myself interacting with one of four popular database tools. I have been resorting to single line commenting for DB2 and Informix. I have created macros in vim to make this slightly more efficient but I was wondering if I am working too hard.
+4
A:
The ISO standard only defines single-line comments beginning with two dashes. Some vendors support C-style commenting (i.e. multiline beginning with /* and ending with */), but it should not be considered "vendor agnostic".
Ben Hoffstein
2009-04-08 02:28:55
+5
A:
C style comments are standard in SQL 2003 and SQL 2008 (but not in SQL 1999 or before). The following DBMS all support C style comments:
- Informix
- PostgreSQL
- MySQL
- Oracle
- DB2
- Sybase
- Ingres
- Microsoft SQL Server
That is not every possible DBMS, but it is more or less every major SQL DBMS. (I'll willingly add notes about any other DBMS that does - or does not - support C style comments.)
The SQL 2003 standard documents comment notations thus:
<comment> ::= <simple comment> | <bracketed comment>
<simple comment> ::=
<simple comment introducer> [ <comment character> ... ] <newline>
<simple comment introducer> ::=
<minus sign> <minus sign> [ <minus sign> ... ]
<bracketed comment> ::=
<bracketed comment introducer> <bracketed comment contents>
<bracketed comment terminator>
<bracketed comment introducer> ::= <slash> <asterisk>
<bracketed comment terminator> ::= <asterisk> <slash>
<bracketed comment contents> ::= [ { <comment character> | <separator> }... ]
<comment character> ::= <nonquote character> | <quote>
IBM Informix Dynamic Server (IDS or Informix) supports C style comments. It also supports '{ ... }' as potentially multi-line comments, except in contexts where it means something else - that something else being a LIST or SET or MULTISET literal. (You might find that DB-Access gets confused by C style comments; that is a separate issue.)
Jonathan Leffler
2009-04-08 02:46:37
Fair enough, it was not clear which SQL standard was being discussed (and my information was outdated). Nonetheless, I still assert that C-style comments are not completely vendor agnostic.
Ben Hoffstein
2009-04-08 02:54:12
I think the best I can hope for is SQL 1999 :( well at least I have vim everywhere.
ojblass
2009-04-08 04:35:37
It depends on the versions you are using, but I think you'll find that the products are way ahead of the standard. I found comments from 2003 for MySQL having (minor) issues with /* comments */, but utility level, not server level. I think you'll find that most servers have supported it since 2000.
Jonathan Leffler
2009-04-08 04:43:59