Thread

1. Re: [QUESTIONS] How fully will subselects be implemented?

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-02-25T14:28:10Z

   > 
   > First, this list is not right place to ask about 6.3 features :)
   > 2nd, subselects within UPDATE are supported.
   
   They are?  I thought he wanted to do:
   
   	update test set x = (select y from taby)
   
   I didn't think we supported that.  Can you confirm that?
    
   > 3rd, there will be separate select (better say - separate re-scan of
   > subquery' plan) for each parent row (I assume that you talk about 
   > correlated subqueries) but this will be more efficient than using 
   > SQL-funcs which do _initialization_, scannig, _closing_ of query' plan
   > for each parent row. When using subqueries performance will be
   > near the same as for performing Nestloop join.
   
   Good.
   
   -- 
   Bruce Momjian                          |  830 Blythe Avenue
   maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
     +  If your life is a hard drive,     |  (610) 353-9879(w)
     +  Christ can be your backup.        |  (610) 853-3000(h)
   
   

2. Re: [QUESTIONS] How fully will subselects be implemented?

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-02-25T14:29:03Z

   > 
   > Herouth Maoz wrote:
   > > 
   > > I'm developing a new app, and I constantly run into the need of updating
   > > things by data in related columns.
   > > 
   > > Since UPDATE doesn't syntatctically support joins, this means that
   > > subselects in UPDATE are a real must.
   
   OK, now I see he only wants the subquery in the where clause.  That
   clearly does work.
   
   -- 
   Bruce Momjian                          |  830 Blythe Avenue
   maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
     +  If your life is a hard drive,     |  (610) 353-9879(w)
     +  Christ can be your backup.        |  (610) 853-3000(h)
   
   

3. Re: [QUESTIONS] How fully will subselects be implemented?

   Vadim Mikheev <vadim@sable.krasnoyarsk.su> — 1998-02-25T15:59:35Z

   Bruce Momjian wrote:
   > 
   > >
   > > First, this list is not right place to ask about 6.3 features :)
   > > 2nd, subselects within UPDATE are supported.
   > 
   > They are?  I thought he wanted to do:
   > 
   >         update test set x = (select y from taby)
   > 
   > I didn't think we supported that.  Can you confirm that?
   
   Oh, this is not supported, sorry.
   And select a, (select b from tab2) from tab1 and so on...
   
   Vadim