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Re: OleDB + parameters = problem [message #19793 is a reply to message #19789]

Wed, 21 January 2009 14:14

mirek is currently offline

mirek
Messages: 14261
Registered: November 2005

Ultimate Member

Novo wrote on Tue, 20 January 2009 17:34

I haven't check how SqlExp with explicit params works, but using parameters with SQL is very important. If you aren't using parameters, then server has to parse your SQL all the time. And very often parsing (and creating an execution plan) is more expensive than executing itself.

Well, have you benchmarked? I have stopped using precompiled Sql expressions when I noticed there is no difference you can really feel.

It might be useful for some very corner cases like when you are querying single value from single table; in all other cases, pushing data over network witll nullify any advantage you can gain by keeping your statement preparsed.

OTOH, it is still supported. Note also that one nice way how to keep very frequent SQL statements precompiled on the server is to have them static:

void Test::remove_person(void)
{
    static Sql stmt("DELETE FROM person WHERE id = ?");

Mirek

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[Message index]

		OleDB + parameters = problem By: Novo on Sat, 17 January 2009 18:16
		Re: OleDB + parameters = problem By: mirek on Mon, 19 January 2009 10:14
		Re: OleDB + parameters = problem By: Novo on Tue, 20 January 2009 23:34
		Re: OleDB + parameters = problem By: mirek on Wed, 21 January 2009 14:14
		Re: OleDB + parameters = problem By: mirek on Wed, 21 January 2009 14:22
		Re: OleDB + parameters = problem By: Novo on Fri, 23 January 2009 05:48
		Re: OleDB + parameters = problem By: Novo on Fri, 23 January 2009 06:03
		Re: OleDB + parameters = problem By: mirek on Fri, 23 January 2009 11:52
		Re: OleDB + parameters = problem By: mirek on Fri, 23 January 2009 11:59
		Re: OleDB + parameters = problem By: Novo on Sat, 24 January 2009 17:58
		Re: OleDB + parameters = problem By: mirek on Sat, 24 January 2009 20:19
		Re: OleDB + parameters = problem By: Novo on Sun, 25 January 2009 04:44
		Re: OleDB + parameters = problem By: Novo on Fri, 23 January 2009 05:55
		Re: OleDB + parameters = problem By: mirek on Fri, 23 January 2009 11:36

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