Delphi Mysql Parameter working with integer not string

Question

I've created the query below as a filter command. But it only works on integer fields. It seems whenever the field is a string it does not work...

The error i keep getting is 'SQL Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'like'%a%''at line 1'

My Code is as follows:

datalive.mail_queue.SQL.Text:='select*from mail_queue where user_id=:user_id and '+fieldname+' like :value';
Addparam(datalive.mail_queue,'user_id',ftString,inttostr(user_id));
Addparam(datalive.mail_queue,'fieldname',ftString,fieldname);
Addparam(datalive.mail_queue,'value',ftString,'%'+edit1.Text+'%');
datalive.mail_queue.Active:=true;

have you tried the query in MySQL? I believe this is not correct - "select*from ...". it should be 'select * from '. — RBA
– RBA, Commented Jun 17, 2015 at 7:37
Hi @RBA, it runs successfully with everything else. So it should not be a problem. I have been typing it like that for years with no problem. — Marcel
– Marcel, Commented Jun 17, 2015 at 9:15

aleroot · Accepted Answer · 2015-06-17 08:08:37Z

1

The problem seems to be in your query string, before the like you are passing a parameter concatenating the string, so I suggest to you to change your query string in this way :

datalive.mail_queue.SQL.Text:=' select * from mail_queue where user_id=:user_id and '+fieldname+' like :value';

You don't have to pass the parameter fieldname since it is a column and not a value :

Addparam(datalive.mail_queue,'user_id',ftString,inttostr(user_id));
Addparam(datalive.mail_queue,'value',ftString,'%'+edit1.Text+'%');

Be sure that the fieldname variable doesn't contain a quoted string, but simply the name of the column to filter on ...

answered Jun 17, 2015 at 8:08

aleroot

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2 Comments

Marcel Over a year ago

I changed it like you suggested. But I am still getting the same error.

Marcel Over a year ago

Also, when changing the '+fieldname+' to :fieldname. It does not give me the error. But something goes wrong with the filter and there are just no records in the db whatsoever... I do not know if that may be a clue

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