Re: Optional join
От | David Fetter |
---|---|
Тема | Re: Optional join |
Дата | |
Msg-id | nXidnVVfXr8X6aGiXTWc-w@speakeasy.net обсуждение исходный текст |
Ответ на | Optional join ("Slawek Jarosz" <Jarosz.S@ems-t.ca>) |
Список | pgsql-sql |
"Slawek Jarosz" <Jarosz.S@ems-t.ca> wrote: > Hi, > I trying to write a query that will join 2 tables. Here's the > concept: > Table 1: table1, primary key pk1 > Table 2: table2, primary key pk2 > One of the fields (f2) in table2 contains either the primary key of > table1 or a NULL value. So normally a pretty basic query: > SELECT table1.*, table2.pk2 > FROM table1, table2 WHERE table2.f2 = table1.pk1; > BUT what I would like to do is show all records of Table 1 even if > there is no match in Table 2. Meaning that the reults could be > table1... table2.pk2 > table1... NULL > Doable? Yes. SELECT table1.*, table2.pk2 FROM table1 LEFT OUTER JOIN table2 ON (table1.pk1 = table2.pk2); HTH :) Cheers, D -- David Fetter david@fetter.org http://fetter.org/ phone: +1 510 893 6100 cell: +1 415 235 3778 Power over a man's subsistence is power over his will. Alexander Hamilton
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