​​http://docwiki.embarcadero.com/RADStudio/XE6/en/TFDMemTable_Questions#Q:_How_can_I_copy_all_records_from_FDQuery_into_FDMemTable_and_edit_them_in_FDMemTable.3F​​

​​http://docwiki.embarcadero.com/RADStudio/XE6/en/Editing_Questions_%28FireDAC%29​​

http://docs.embarcadero.com/products/rad_studio/firedac/frames.html?frmname=topic&frmfile=index.html

TFDMemTable is faster than TClientDataSet.

 FDQuery.OpenOrExecute

FDQuery Params

FDQuery->ParamByName("kl")->Value = edtkl->Text;
FDQuery->Params->Items[0]->Value = cboyhmc->Text;
FDQuery->Params->operator[](0)->Value = 0;


 

FDConnection1.SQL（"INSERT INTO MyTable（Name， Age） VALUES（:name， :age）"， [""AAA""， 11]）;
FDConnection1.SQLScalar（""SELECT Age FROM MyTable WHERE Name = :x""， [""BBB""]）;


 

FDMemTable1.CopyDataSet(DataSet1, [coStructure, coRestart, coAppend]);


copy all records from FDQuery into FDMemTable

FDQuery1.FetchOptions.Undirectional := False;

FDQuery1.Open;
FDQuery1.FetchAll;
FDMemTable1.Data := FDQuery1.Data;


remove dataset records without removing them from the database




A: You can work directly with internal dataset data storage. It is accessible through TFDDataSet.Table property. For example, to delete the row with index 3 do the following:




FDQuery1.Table.Rows[3].Free;
FDQuery1.UpdateCursorPos;
FDQuery1.Resync([]);


For example, to delete the current record, do the following:




FDQuery1.UpdateCursorPos;
FDQuery1.GetRow.Free;
FDQuery1.UpdateCursorPos;
FDQuery1.Resync([]);


Assigning TField.CustomConstraint does not work. What is wrong?

Q: Appending constraint via:




FDQuery.FieldByName('FIELD_NAME').CustomConstraint := 'FIELD_NAME > 1';
FDQuery.UpdateConstraints;
FDQuery.Table.Constraints.Check(FDQuery.GetRow(), rsModified, ctAtEditEnd);


Is not working and an exception is not raised.

A: That is OK (explanation will follow).

Q: But:




FDQuery.Constraints.Add.CustomConstraint := 'FIELD_NAME > 1';
FDQuery.UpdateConstraints;
FDQuery.Table.Constraints.Check(FDQuery.GetRow(), rsModified, ctAtEditEnd);


Is working! Why?

A: Also OK.

Q: What exactly do ctAtEditEnd and ctAtColumnChange mean?

A: These enums are specifying the event when FireDAC should check constraints:

  • ctAtEditEnd - the Post is called
  • ctAtColumnChange - a field value is modified

Now the explanation:




FDQuery.FieldByName('FIELD_NAME').CustomConstraint := 'FIELD_NAME > 1';


This adds a field-level constraint. They are checked at ctAtColumnChange event only.




FDQuery.Constraints.Add.CustomConstraint := 'FIELD_NAME > 1';


This adds a record-level constraint. They are checked at ctAtEditEnd event only.



FDQuery1.Command.CommandKind := skInsert;FDQuery1.ExecSQL;

FDQuery带参数Open

FDQuery1.Open('select * from tt where id=:id',[0]);

 Variant locvalues[1];

 locvalues[0] = Variant("01");

 FDQuery1->Open("select * from table where id=:id", locvalues, 0);