Delphi / Query组件-将长字符串（800个字符）分配给sql.text属性，将SQL修剪为仅326个字符

Question

I use Delphi/NexusDB and I build SQL (about 800 char long) at run time then I pass it to the nexusdb query.sql.text property to execute it but I found error of invalid token on execution.

I pass SQL like this

Query.SQL.Text := VarStrSQL; // <<---- string variable holding the SQL

when I traced I found SQL string in the Query.SQL.Text is trimmed to 326 character !! While the string variable that hold the SQL is complete and fine but when I assign that variable to query.sql.text only 326 character passed and of course this result in an error for invalid SQL syntax

Please advise why the SQL string trimmed like that ?

Update: * I tried memo1.lines.text := VarStrSQL and the memo component also display the string trimmed !! is it possible a character in my string cause that !! a bug in Delphi 2010 that cause TStrings to trim my string ? *

Thanks

Answer 1

Sounds like a bug in DB provider itself. There is no such limitation in TQuery .

My advice shall be to use small SQL, but bound parameters to set the data.

Instead of

Query.SQL.Text := 'INSERT INTO Store_Information (store_name, Sales, Date)
VALUES ('Los Angeles ... ... ...', 900, '10-Jan-1999')';

code

Query.FieldByName('store').AsString := 'Los Angeles ... ... ...'; // here you should have no limitation
Query.FieldByName('sales').AsInteger := 900;
Query.FIeldByName('Date').AsDAteTime := Now;
Query.SQL.Text := 'INSERT INTO Store_Information (store_name, Sales, Date)
VALUES (:store,:sales,:date)';

And your request will be faster, since the statement could be preparated by the engine, then reused.

Answer 2

I found the problem: It is nxtChar Fields when they are null they have the value #0 and that cause string trimming

however although I check for null like this varisnull() the char fields was able to skip this trap function !!! which makes me go around myself for hours finally I now check them like this

If <nxtChar field> = #0 then <nxtChar field> = '' (or <nxtChar field> = null)