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Use Parameters in TLiteQuery
Posted: Sun 27 Jan 2013 14:18
by bjaustin
I am creating a login form and I need to set the parameters of a query component through the code. How should I do that (both the parameters are UnicodeStrings)?
Re: Use Parameters in TLiteQuery
Posted: Mon 28 Jan 2013 10:08
by AlexP
Hello,
You should enable the UseUnicode option in LiteConnection before connectiong to the database and assign parameter values using the asSttring property.
Code: Select all
LiteConnection1.Options.UseUnicode := True;
LiteConnection1.Connect;
LiteQuery1.SQL.Text := 'select :p1';
LiteQuery1.ParamByName('p1').AsString := Edit1.text;
LiteQuery1.Open;
Re: Use Parameters in TLiteQuery
Posted: Thu 31 Jan 2013 23:01
by bjaustin
Thank you. I have another question. How would one check to see if a query returned results?
Re: Use Parameters in TLiteQuery
Posted: Fri 01 Feb 2013 11:16
by AlexP
Hello,
To define DataSet or not, you can use two properties: IsEmpty and RecordCount,
the first one returns True if the DataSet is empty, the second one - 0, for example:
Code: Select all
LiteQuery1.SQL.Text := 'select :p1 where 1<>1';
LiteQuery1.ParamByName('p1').AsInteger := 1;
LiteQuery1.Open;
ShowMessage(VarToStr(LiteQuery1.IsEmpty)); //True
ShowMessage(VarToStr(LiteQuery1.RecordCount = 0)); //True
Re: Use Parameters in TLiteQuery
Posted: Sat 02 Feb 2013 13:31
by bjaustin
When trying the code that you gave:
Code: Select all
ShowMessage(VarToStr(LiteQuery1.IsEmpty));
I get True, but it should return False as the values that I enter
are in my database.
The database values are
And my code is
Code: Select all
this->LiteQuery1->ParamByName("uname")->AsString = uname; //admin
this->LiteQuery1->ParamByName("passw")->AsString = pwd; //admin
ShowMessage(VarToStr(this->LiteQuery1->IsEmpty()));
Re: Use Parameters in TLiteQuery
Posted: Mon 04 Feb 2013 11:40
by AlexP
Hello,
Please check that, after opening the DataSet, the RecordCount property returns a value greater than 0, and that the data in the database is equal to that you set in the parameters (no spaces, the case of symbols is the same).
Code: Select all
this->LiteQuery1->ParamByName("uname")->AsString = uname; //admin
this->LiteQuery1->ParamByName("passw")->AsString = pwd; //admin
this->LiteQuery1->Open;
ShowMessage(VarToStr(this->LiteQuery1->IsEmpty()));
ShowMessage(VarToStr(this->LiteQuery1->RecordCount));
assert((this->LiteQuery1->RecordCount = 0) = this->LiteQuery1->IsEmpty());
Re: Use Parameters in TLiteQuery
Posted: Fri 08 Feb 2013 09:52
by ecig12
Version 1.6.4 has add the TLiteSQL and TLiteQuery.
Data base connection make sure.
Requirement is C++,Turbo.
Re: Use Parameters in TLiteQuery
Posted: Fri 08 Feb 2013 13:42
by AlexP
Hello,
We cannot reproduce the problem, please send the DB file to alexp*devart*com