Re: LIMIT 1 FOR UPDATE or FOR UPDATE LIMIT 1?
От | Bruce Momjian |
---|---|
Тема | Re: LIMIT 1 FOR UPDATE or FOR UPDATE LIMIT 1? |
Дата | |
Msg-id | 200208260031.g7Q0VCC24924@candle.pha.pa.us обсуждение исходный текст |
Ответ на | LIMIT 1 FOR UPDATE or FOR UPDATE LIMIT 1? (Magnus Enbom <dot@rockstorm.se>) |
Список | pgsql-sql |
I found this email from April. It properly points out that our LIMIT/FOR UPDATE ordering doesn't match MySQL's, and MySQL's looks more correct, specifically that the FOR UPDATE is after the LIMIT. Our grammar is: | select_clause sort_clause opt_for_update_clause opt_select_limit How do we want to deal with this? I tried allowing both orderings with the attached patch but got: bison -y -d gram.y conflicts: 4 shift/reduce, 5 reduce/reduce --------------------------------------------------------------------------- Magnus Enbom wrote: > Hi, > > I've just been hit by a small but annoying difference between postgres(7.2) > and mysql(4.x). > In postgresql you do: > > SELECT * FROM table FOR UPDATE LIMIT 1; > > and in mysql you do: > > SELECT * FROM table LIMIT 1 FOR UPDATE; > > Is it possible for postgres to accept the mysql syntax as well? > It's not that many databases that implement LIMIT, so it would be nice if the > ones that do have the same syntax(or can accept each others variants). > > -- Magnus > > ---------------------------(end of broadcast)--------------------------- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 Index: gram.y =================================================================== RCS file: /cvsroot/pgsql-server/src/backend/parser/gram.y,v retrieving revision 2.360 diff -c -r2.360 gram.y *** gram.y 19 Aug 2002 15:08:47 -0000 2.360 --- gram.y 26 Aug 2002 00:29:24 -0000 *************** *** 4114,4123 **** --- 4114,4135 ---- nth(0, $4), nth(1, $4)); $$ = $1; } + | select_clause sort_clause opt_select_limit opt_for_update_clause + { + insertSelectOptions((SelectStmt *) $1, $2, $4, + nth(0, $3), nth(1, $3)); + $$ = $1; + } | select_clause for_update_clause opt_select_limit { insertSelectOptions((SelectStmt *) $1, NIL, $2, nth(0, $3), nth(1, $3)); + $$ = $1; + } + | select_clause opt_select_limit for_update_clause + { + insertSelectOptions((SelectStmt *) $1, NIL, $3, + nth(0, $2), nth(1, $2)); $$ = $1; } | select_clause select_limit
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