How to use FieldName and FieldValue in Delphi XE2?
In this delphi programming tutorial, we will come to know how to use FieldName and FieldValue in delphi. Sometimes while coding in delphi, we need to get the field or column name of the table depending upon some certain conditions. In this case FieldName and FieldValue come into play.
In the following delphi code, we have created a delphi function which will fetch various columns from a table in database and will return the name of that column. For example, following delphi program gets ColA, ColB, ColC, ColD from a table named tblABC. After getting all the columns, it iterate through the column list and finds out which one is null and returns it. If it finds no column which is null, it returns empty string.
(Note: ColA, ColB, ColC, ColD are numeric columns, so I am checking for null. If your columns are varchar, you can use '' for checking empty column)
Delphi Program to show usage of FieldName and FieldValue
function TForm.MyDelphiFunction : String;
var
i : integer;
begin
try
Result := '';
with qryABC do
begin
Close;
SQL.Clear;
SQL.Text := 'SELECT ColA, ColB, ColC, ColD FROM tblABC WHERE ID = :ID';
ParamByName('ID').AsString := anyID;
Open;
var
i : integer;
begin
try
Result := '';
with qryABC do
begin
Close;
SQL.Clear;
SQL.Text := 'SELECT ColA, ColB, ColC, ColD FROM tblABC WHERE ID = :ID';
ParamByName('ID').AsString := anyID;
Open;
if RecordCount > 0 then
begin
for i:=0 to FieldCount -1 do
begin
if (Fields[i].Value) = Null then
begin
Result := Fields[i].FieldName;
Break;
end;
end;
end;
begin
for i:=0 to FieldCount -1 do
begin
if (Fields[i].Value) = Null then
begin
Result := Fields[i].FieldName;
Break;
end;
end;
end;
Close;
end;
except
on E : Exception do
begin
Showmessage('Error occured in function MyDelphiFunction: ' + E.Message);
Result := '';
end;
end;
end;
end;
except
on E : Exception do
begin
Showmessage('Error occured in function MyDelphiFunction: ' + E.Message);
Result := '';
end;
end;
end;
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