Get Column names with Delphi (Dbexpress) - sql

Question

I'm using this sql command to get column names :
select COLUMN_NAME from
INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = 'MyTableName'
but i don't know how can i using the executed SQL command results !
for example , this way doesn't work to extract the column names as a string value and i got this error = Operation Not Supported :
for i := 1 to Qry1.RecordCount do
begin
end;

Answer 1

Another way you can do this is to query the table itself to get an empty dataset, and then loop through the fields in that dataset.
A query like this will return the table structure with no records in it:
Qry1.SQL.Text := 'SELECT * FROM MyTableName WHERE 1<>1';
Qry1.Open;
And a loop like this will iterate through each field
for I := 0 to Qry1.FieldCount-1 do
begin
X := Qry1.Fields[I].FieldName;
// and do whatever you want with X
end;

Answer 2

Something like this would work for a TADOQuery (not sure if it's different for dbExpress):
Qry1.Open;
while not Qry1.Eof do begin
// do whatever with Qry1.Fields[0].AsString here
Qry1.Next;
end;
Qry1.Close;

Answer 3

From what I understand you are unable to retreive the retults.
Qry1.First;
while not Qry1.Eof do
begin
X := Qry1.FieldByName('column_name').AsString;
Qry1.Next;
end;
This is a piece of code which has always worked for me
Or you can read this link which explains why the exception is thrown when calling .RecordCount (http://edn.embarcadero.com/article/28494)
To sum it up it suggests that your query is case-sensitive and you should probably check the table name (MyTableName)

Answer 4

agree with Rob McDonell, in order to list the column name of a field, I'll use that
as in my code I wrote something like this
Procedure blablabla;
var i:integer;
begin
..... {some code here}
SQLQuery1.Open;
for i := 0 to SQLQuery1.FieldCount-1 do
begin;
Memo1.Lines.Append(SQLQuery1.Fields[i].DisplayName);
end;
SQLQuery1.Close;
.... {some code here}
end;