How do you hide/show cxGrid column in code ? I tried : cxGrid2dbtableview1.Columns[mycolumnname].Visible :=False;
But it does not seem to apply.What am I missing here ?
If you want to identify the column by fieldname
var
C:TcxGridDBColumn;
begin
C := View.GetColumnByFieldName('cx1');
if Assigned(C) then C.Visible := not C.Visible;
end;
The Columns collection is indexed by integer, not column name. Instead, try cxGrid2dbtableview1.Columns[mycolumnname.index].Visible :=False;
The other way is to set the column object's Visible property directly, cxGrid1Column1.Visible := False;
For columns created at run time, use Ken's answer.
Related
When using the 'while not TADOQuery.Eof' with an microsoft Excel Workbook, it's including rows which are completely empty. Is there a way to stop including any rows that are completely blank as I don't need them?
You could exclude blank lines in the SQL used to open the spreadsheet. If the first row contains column headings like 'Column1', 'Column2', etc then the following SQL will not return rows where the value in the first column is blank
select * from [sheet1$]
where Column1 <> ''
Obviously the SQL could be a bit more specific (in terms of column values) about what you regard as constituting a blank row.
You'll have gathered that there are various ways to deal with variations in the contents of the column headers, but as the other answer shows, these are likely to be far more verbose than simply skipping blank rows inside the body of your main while not EOF loop to read the table contents, so I can't really see any benefit to not doing it by just skipping the blank rows.
Btw, ime the Excel data accessible via SQL behaves as though the query is automatically restricted to the UsedRange range in the Excel COM interface.
Original answer:
If I understand you correctly and you want to exclude empty rows after the query is opened, then next approach may help (but I think, that you should exclude these rows with SQL statement, as in #MartynA's answer). Here, empty rows are all rows, which have Null value for all fields.
procedure TForm1.btnDataClick(Sender: TObject);
var
i: Integer;
empty: Boolean;
begin
qry.First;
while not qry.Eof do begin
// Check for empty row. Row is empty if all fields have NUull value.
empty := True;
for i := 0 to qry.FieldCount - 1 do begin
if not qry.Fields[i].IsNull then begin
empty := False;
Break;
end{if};
end{for};
// Read record data if record is not empty
if not empty then begin
// Your code here ...
end{if};
// Next record
qry.Next;
end{while};
end;
Update:
It's an attempt to improve my answer. If the table structure is not known, you can query the table with always false WHERE clause to get this structure and generate an SQL statement dynamically:
procedure TForm1.btnDataClick(Sender: TObject);
var
i: Integer;
where: string;
begin
// Get column names
qry.Close;
qry.SQL.Clear;
qry.SQL('SELECT * FROM [SheetName] WHERE 1 = 0');
try
qry.Open;
except
ShowMessage('Error');
end{try};
where := '';
for i := 0 to qry.FieldCount - 1 do begin
where := where + '(' + qry.Fields[i].FieldName + ' <> '''') AND ';
end{for};
where := 'WHERE ' + Copy(where, 1, Length(where) - 5);
// Read data without "empty" rows
qry.Close;
qry.SQL.Clear;
qry.SQL('SELECT * FROM [SheetName] ' + where);
try
qry.Open;
except
ShowMessage('Error');
end{try};
end;
So, I have a table in database like this :
number varchar2 (50)
activities varchar2 (50)
value number
flag varchar(2)
for flag, I have 2 options which means :
1=debit and 2=credit.
assume I wanted to create a report using fastreport 4, I'll make the report look like this :
my question is, how do you code in fastreport so that every value with flag 1 will show up in debit column and value with flag 2 shows up in credit column?
I am using delphi 7 by the way. Thanks!
One possible solution is to use band's OnBeforePrint event:
procedure MasterData1OnBeforePrint(Sender: TfrxComponent);
begin
if <reportdataset."FLAG"> = '1' then begin
MemoDebit.Text := FormatFloat('#0.00', <reportdataset."VALUE">);
MemoCredit.Text := FormatFloat('#0.00', 0);
end
else if <reportdataset."FLAG"> = '2' then begin
MemoDebit.Text := FormatFloat('#0.00', 0);
MemoCredit.Text := FormatFloat('#0.00', <reportdataset."VALUE">);
end
else begin
MemoDebit.Text := FormatFloat('#0.00', 0);
MemoCredit.Text := FormatFloat('#0.00', 0);
end;
end;
FastReport can include an IIF statement in a TfrxMemoView.
Your report band will include two fields, one for the Debit column and one for the credit column.
Then in the debits field, you will enter:
[IIF(<Data."flag"> = '1', <Data."value">, '')]
And in the credits field:
[IIF(<Data."flag"> = '2', <Data."value">, '')]
The IIF statement can also be used inside a Sum() call in footers to get the correct totals.
[SUM(IIF(<Data."flag"> = '1', <Data."value">, 0))]
Well, this seems a little tricky (if not imposible). I'm trying to make my DBGrid sort its data by clicking on column's title.
The thing is that I'm (sadly) working with Delphi 3, I'm not using ADO DataSets and the query gets a lot of rows, thus I can't reopen my TQuery changing the order by clause on clicks.
Someone has implemented something like this?
This is actually done by sorting the dataset, and then the grid reflects the change. It can be done easily enough by creating an index on the dataset field for that column. Of course, this can only be done on a dataset that supports index sorting, such as TClientDataset.
On the TDBGrid's OnTitleClick method you can do something like...
procedure TfmForm1.DBGrid1TitleClick(Column: TColumn);
var
i: Integer;
begin
// apply grid formatting changes here e.g. title styling
with DBGrid1 do
for i := 0 to Columns.Count - 1 do
Columns[i].Title.Font.Style := Columns[i].Title.Font.Style - [fsBold];
Column.Title.Font.Style := Column.Title.Font.Style + [fsBold];
with nxQuery1 do // the DBGrid's query component (a [NexusDB] TnxQuery)
begin
DisableControls;
if Active then Close;
for i := 0 to SQL.Count - 1 do
if (Pos('order by', LowerCase(SQL[i])) > 0) then
//NOTE: ' desc' The [space] is important
if (Pos(' desc',LowerCase(SQL[i])) > 0) then
SQL[i] := newOrderBySQL
else
SQL[i] := newOrderBySQL +' desc';
// re-add params here if necessary
if not Active then Open;
EnableControls;
end;
end;
There are plenty of ways in which you could optimise this I'm sure however it depends on the capabilities of the components you use. The example above uses a query component though if you used a table component you'd change the index used instead of the 'order by' clause.
The handling of the SQL here is a very basic version. It does not handle things like SQL batch statements, resulting in possible multiple 'order by..' clauses or commented SQL statements i.e. ignoring bracketed comments "{..}" or single line comments "//"
Regards
Delphi 3 have TClientDataset. And TQuery can use explicitly created indexes on the database to order data on the IndexName property.
Here are some examples of how to do this: Sorting records in Delphi DBGrid by Clicking on Column Title .
As already mentioned, sorting is quite easy if you are using a TClientDataSet (cds.IndexFieldNames := Column.FieldName in the OnTitleClick of the TDBGrid). However if you are not able to do this you can either regenerate your query (which you have stated you don't want to do) or obtain a more advanced data grid such as Express Quantum Grid (which I think allows you to sort).
On the TDBGrid's OnTitleClick method you can write this simple code:
procedure TForm1.DBGrid3TitleClick(Column: TColumn);
var
cFieldName:string;
begin
cFieldName:= DBGrid3.SelectedField.FieldName;
AdoDataset1.Sort:=cFieldName;
end;
example: (https://www.thoughtco.com/sort-records-in-delphi-dbgrid-4077301)
procedure TForm1.DBGrid1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
var
pt: TGridcoord;
begin
pt:= DBGrid1.MouseCoord(x, y);
if pt.y=0 then
DBGrid1.Cursor:=crHandPoint
else
DBGrid1.Cursor:=crDefault;
end;
procedure TForm1.DBGrid1TitleClick(Column: TColumn);
var
cFieldName:string;
begin
Adotable1.Sort := Column.Field.FieldName;
end;
If you are using a combination of TFDQuery, TDataSource and TDBGrid you can order with this easy way!
procedure TFrmGer.DBGridTitleClick(Column: TColumn);
begin
OrderByTitle(MyFDQuery, Column);
end;
Put it in a helper file so you can use it latter again.
procedure OrderByTitle(AQuery: TFDQuery; Column: TColumn);
begin
AQuery.IndexFieldNames := Column.DisplayName;
end;
Ascending and Descending Mode
if Pos('DESC',PChar(Q2.Sort))>0 then
Q2.Sort:=Column.FieldName + ' ASC'
else
Q2.Sort:=Column.FieldName + ' DESC';
Since Embarcadero's NNTP server stopped responding since yesterday, I figured I could ask here: I work with a non-DB-aware grid, and I need to loop through a dataset to extract the number of columns, their name, the number of rows and the value of each fields in each row.
I know to read the values for all the fields in each row, but I don't know how to extract column-related information. Does someone have some code handy?
procedure TForm1.FormCreate(Sender: TObject);
var
index : Integer;
begin
With ASQLite3DB1 do begin
DefaultDir := ExtractFileDir(Application.ExeName);
Database := 'test.sqlite';
CharacterEncoding := 'STANDARD';
Open;
end;
With ASQLite3Query1 do begin
ASQLite3Query1.Connection := ASQLite3DB1;
SQL.Text := 'CREATE TABLE IF NOT EXISTS mytable (id INTEGER PRIMARY KEY, label VARCHAR)';
ExecSQL;
SQL.Text := 'INSERT INTO mytable (label) VALUES ("dummy label")';
ExecSQL;
SQL.Text := 'SELECT id AS Identification, label AS Label FROM mytable';
Open;
//How to get column numbers + names to initialized grid object?
for index := 0 to ASQLite3Query1. - 1 do begin
end;
for index := 0 to FieldCount - 1 do begin
ShowMessage(Fields[index].AsString);
end;
end;
end;
Thank you.
Number of fields and their names could be acquired as follows:
procedure TForm1.Button1Click(Sender: TObject);
begin
with Query1 do
begin
ShowMessage(IntToStr(FieldCount));
ShowMessage(Fields[0].FieldName);
end;
end;
You can checkout TFieldDef for more detail info about the field.
dataset.FieldDefs[0] has properties like DataType and Size.
If what you're looking for is a list of field names, try creating a TStringList and passing it to the TDataset.Fields.GetFieldNames procedure.
If you want more information about fields, the TFields object (ASQLite3Query1.Fields) has a default property and a Count property, so you can use it like an array, and an enumerator, both of which can be used to loop over each TField object and retrieve its metadata.
I've got an in-memory dataset with several fields, one of which is a primary key that another dataset references as a foreign key. Thing is, the master dataset can have multiple references to the detail dataset. (This is modeling an object that contains a dynamic array of other objects.)
If there was only one of each sub-object, I could make the right association with the KeyFields and LookupKeyFields properties of the reference field in the master dataset, but that's only designed to return one result. I want to load all the records whose primary key matches the right ID key and display them in a listbox.
I thought a TDBListBox would help with this, but it turns out that's not what they do. So how would I populate a listbox or similar control with the result set of a multiple-match check like that for further editing? I want something similar to the result of a SQL query like this:
select field1, field2, field3
from client_dataset
where client_dataset.primary_key = master_dataset.id
Only thing is, this is done entirely with in-memory datasets. No real databases are being used here. Does anyone know how this can be done?
The dataset has a Filter property which can be set with a condition. You also have to set the filtered flag on true. And with he datacontrols you can select which fields are visible.
So:
var
c : TColumn;
begin
clientdataset.Filter := Format('primary_key = %d', [master_dataset.id]);
clientdataset.Filtered := True;
c := DBGrid1.Columns.Add;
c.FieldName := 'field1';
c := DBGrid1.Columns.Add;
c.FieldName := 'field2';
c := DBGrid1.Columns.Add;
c.FieldName := 'field3';
end;
Should do the trick.