Unspecified Error when search a table for a string in sql delphi using parameters - Delphi SQL - sql

Question

there. I am trying to search for a string contained in any column of a sql table by adding all the Fieldnames to the WHERE clause using a for loop. Also I use parameters to protect against SQL injection. But when I run I get an error like this:
Unspecified error
How can this be fixed and what is the problem (Not necessarily in that order). Here is my code. I am running Delphi 7
procedure TfrmView.edtSearchChange(Sender: TObject);
var
i, i2: integer;
obj: TEdit;
QueryText: string;
begin
obj:= Sender as TEdit;
with dmInfo do
begin
qryInfo.SQL.Clear;
qryInfo.SQL.Add('SELECT * FROM ' + tableName);
qryInfo.Open;
tblInfo.SQL.Clear;
tblInfo.SQL.Add('SELECT * FROM ' + tableName);
tblInfo.SQL.Add('WHERE (' + qryInfo.Fields[0].FieldName + ' LIKE :SQuery0)');
QueryText:= '%' + obj.Text + '%';
tblInfo.Parameters.ParamByName('SQuery0').Value:= QueryText;
ShowMessage(QueryText);
ShowMessage(tblInfo.Parameters.ParamByName('SQuery0').Value);
for i:= 1 to qryInfo.FieldCount - 1 do
begin
tblInfo.SQL.Add(' OR (' + qryInfo.Fields[i].FieldName + ' LIKE :SQuery' + IntToStr(i) + ')');
tblInfo.Parameters.ParamByName('SQuery' + IntToStr(i)).Value:= '%' + obj.Text + '%';
end;
tblInfo.Open;
end;

Answer 1

The whole code makes no sense.
You let the code run every time you change a letter.
run by an onChange event
five input/letter to the edtSearch input field means the code is executed five times without interruption immediately
If you delete all content in the edtSearch input field at once,
which is also a change event.
This time it runs with an empty edtSearch.text
How can you expect that this works without exceptions
You open each time two tables without to close them before.
you are using a variable, which suggests that this event is also
connected to other TEdits.
obj: TEdit;
obj:= Sender as TEdit;
You clear the SQL on an open table.
you have two tables the first one does nothing more than SQL.clear
and open
You're using fields from first table and create the SQL for second table
Even if both tables are the same, it makes no sense to use the fields
from the first table.
It is confusing, misleading and unnecessary.
First of all remove the code out of the onChange event
What you want to do with this code
to search for values on all fields from the tblInfo
can be done without the first tabel qryInfo
you do not need to increment the params.
Do not create the params all the time from SQuery1 to maybe SQuery100
if you only use one param (the search value is always the same)
You can set all params with a single use tblInfo.Parameters.ParamByName() before the tblInfo.Open
but NOT in the loop.
This will replace all params :SQuery all at once with the value
SQL.Text :
SELECT * FROM tableName
WHERE (IDmember LIKE :SQuery)
OR (memberName LIKE :SQuery)
OR (petName LIKE :SQuery)
OR (Address LIKE :SQuery)
Maximum Length Of An SQL Statement
Is different from database to database
How many OR clauses can I use in a single WHERE condition in MySql query?
I know there was a limit in the past.
But now the experts knowledge is different
only one of the opinions
The truth is that it's limited to the resources available on the
database, the size of the data set in question, the indexes being
addressed (or lack thereof) and the complexity of each clause.
If your goal is to find a person record that meets multiple criteria,
I am willing to bet you won't run in to a limit. You could easy OR
condition with 20 to 30 conditions and no user is going to provide
more that that / person records won't have more than one that meets
that many conditions.