NullStr to NULL in SQLQuery

[BSaidus]

Hello.

Given this code:

Code: Pascal  [Select][+][-]

1. // v_int : TLongIntFirld
2. // v_txtc: TStringField
3. // v_txtt: TMemoField
4.  
5. const
6.   CSQL = 'INSERT INTO uc_temp (v_int, v_txtc, v_txtt) VALUES (%d, %s, %s);';
7. var
8.   LtextSQL: string;
9.   Lf1: LongInt;
10.   Lf2, Lf3: String;
11. begin
12.  
13.   if not TryStrToInt(Edit1.Text, Lf1) then
14.   begin
15.     // Lf1 = Null;
16.   end;
17.      
18.   Lf2 := Edit2.Text;
19.   if Trim(Lf2) = '' then
20.   begin
21.     // Lf2 = Null;  
22.   end;
23.  
24.   Lf3 := Memo2.Text;
25.   if Trim(Lf3) = '' then
26.   begin
27.     // Lf3 = Null;      
28.   end;  
29.  
30.  
31.   LtextSQL := Format(CSQL, [Lf1, Lf2, Lf3]);
32.  
33.   Memo1.Append(LtextSQL);
34.  
35.   Self.ZQuery1.SQL.Clear;
36.   // ...
37.  
38. end;
39.  

My Question is, How to Convert Empty Value ( for string = '', for Integer = '' ) to Null, in order to when executing
sql statement, the Empty value will be replaced by NULL.

IN my exemple, I use Edit & Memo to get input values, if they are empty then I Format the query with NULL
 
  Ie:

Code: Pascal  [Select][+][-]

1.  
2.   LtextSQL := INSERT INTO uc_temp (v_int, v_txtc, v_txtt) VALUES (NULL, NULL, NULL);
3.  

 


PS: I do not want to construct the query using string concatination.
 

[dseligo]

Use parameters.

You use them like this:

Code: Pascal  [Select][+][-]

1.   CSQL = 'INSERT INTO uc_temp (v_int, v_txtc, v_txtt) VALUES (:v_int, :v_txtc, :v_txtt)';
2. ...
3. ParamByName('v_int').AsInteger := 1;
4. ParamByName('v_txtc').AsString := 'abc';
5. ParamByName('txtt').AsString := 'cde';
6.  

If you want null value, you do it like this:

Code: Pascal  [Select][+][-]

1. ParamByName('v_int').Clear;

[BSaidus]

Thank you.
I'll do it like that.