> On Wed, 2003-03-19 at 20:32, Oleg Bartunov wrote: >> On Wed, 19 Mar 2003, Alvaro Herrera wrote: >> > stringA||COALESCE(NULL, '') >> > >> >> we don't know in advance if it's NULL or not. > > Right, that's the point of COALESCE: the first non-NULL argument is > returned -- so if the first argument to COALESCE happens to be non-NULL, > COALESCE has no effect.
I tried this with a txtidx column type: tsearch=# select coalesce(NULL,''); case ------ (1 row) tsearch=# select coalesce(NULL,'hi'); case ------ hi (1 row) tsearch=# select title_fts from article; title_fts ---------------------------------- '2':3A 'tsearch':1A 'version':2A 'easi':1A 'implement':2A (3 rows) tsearch=# select coalesce('',title_fts) from article; ERROR: Void value tsearch=# select coalesce('hi',title_fts) from article; case ------ 'hi' 'hi' 'hi' (3 rows) --- Note the error: "ERROR: Void value" above. Why is that happening? -- Thomas ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]