Re: Informix SQL question

I think the optimizer takes care of that, but I'm not sure. Candy McCall <candym@olcinc.com> wrote in article <6l58c9$j8v$1@news.xmission.com>... > > This is a multi-part message in MIME format. > > ------=_NextPart_000_004F_01BD8F43.26C88C20 > Content-Type: text/plain; > charset="iso-8859-1" > Content-Transfer-Encoding: quoted-printable > > I have a simple question. Suppose you have a table whose primary key is = > a composite > key of the columns col1,col2,col3,col4 (primary key is in that order). = > If you do a query to=20 > fetch a record by the primary key, does it matter what order you ask for = > the columns=20 > in the where clause? > > For example, does =20 > SELECT * FROM someTable WHERE col4=3D? AND col1=3D? AND > col2=3D? AND col3=3D? =20 > get the record as efficiently as the statement > SELECT * FROM someTable WHERE col1=3D? AND col2=3D? AND col3=3D? AND= > col4=3D? > > I always order the columns in the where clause in the order of the = > primary key or the > index I'd like the optimizer to use. I've noticed in the IBM Visual Age = > for Java that some > of the code generated to retrieve a row by a primary key may mix up the = > order. > > Thanks! > > Candy > -- > Candy McCall > ONLINE Computing, Inc. > (candym@olcinc.com) > > ------=_NextPart_000_004F_01BD8F43.26C88C20 > Content-Type: text/html; > charset="iso-8859-1" > Content-Transfer-Encoding: quoted-printable > > <!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML//EN"> > <HTML> > <HEAD> > > <META content=3Dtext/html;charset=3Diso-8859-1 = > http-equiv=3DContent-Type> > <META content=3D'"MSHTML 4.71.1712.3"' name=3DGENERATOR> > </HEAD> > <BODY bgColor=3D#d8d0c8> > <DIV><FONT color=3D#000000 size=3D2>I have a simple question.&nbsp; = > Suppose you have=20 > a table whose primary key is a composite</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>key of the columns = > col1,col2,col3,col4 (primary=20 > key is in that order). If you do a query to </FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>fetch a record by the </FONT><FONT = > color=3D#000000=20 > size=3D2>primary key, does it matter what order you ask for the columns=20 > </FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>in the where clause?</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2></FONT>&nbsp;</DIV> > <DIV><FONT color=3D#000000 size=3D2>For example, does&nbsp;&nbsp; = > </FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>&nbsp;&nbsp;&nbsp; SELECT * FROM = > someTable WHERE=20 > col4=3D? AND col1=3D? AND</FONT></DIV> > <DIV><FONT color=3D#000000 = > size=3D2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=20 > col2=3D? AND col3=3D?&nbsp;&nbsp;</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>&nbsp;get the record as efficiently = > as the=20 > statement</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>&nbsp;&nbsp;&nbsp; SELECT * FROM = > someTable WHERE=20 > col1=3D? AND col2=3D? AND col3=3D? AND col4=3D?</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2></FONT>&nbsp;</DIV> > <DIV><FONT color=3D#000000 size=3D2>I always order the columns in the = > where clause=20 > in the order of the primary key or the</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>index I'd like the optimizer to = > use.&nbsp; I've=20 > noticed in the IBM Visual Age for Java that some</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>of the code generated to retrieve a = > row by a=20 > primary key may mix up the order.</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2></FONT>&nbsp;</DIV> > <DIV><FONT color=3D#000000 size=3D2>Thanks!</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2></FONT>&nbsp;</DIV> > <DIV><FONT color=3D#000000 size=3D2>Candy</FONT></DIV> > <DIV><FONT color=3D#000000 size=3D2>--<BR>Candy McCall<BR>ONLINE = > Computing,=20 > Inc.<BR>(<A=20 > href=3D"mailto:candym@olcinc.com">candym@olcinc.com</A>)</FONT></DIV></BO= > DY></HTML> > > ------=_NextPart_000_004F_01BD8F43.26C88C20-- > >