How to ignore some parameters in TQuery

Question

If i have a SQL statement like below

SELECT * FROM myTable WHERE CID = :vCID AND DataType = :vDataType

And usually i use TQuery to get some data like below

aQuery.ParamByName('vCID').Value := '0025';
aQuery.ParamByName('vDataType').AsInteger := 1;

But how can i ignore the "CID" key to get a SQL like

SELECT * FROM myTable WHERE DataType = :vDataType

I've try the below synctax, but failed

aQuery.ParamByName('vCID').Value := '%';
aQuery.ParamByName('vDataType').AsInteger := 1;

Please help me out, thank you.

Answer 1

The best option is to simply use separate queries:

aQueryBoth.SQL.Text := 'SELECT * FROM myTable WHERE CID = :vCID AND DataType = :vDataType';
...
aQueryBoth.ParamByName('vCID').Value := '0025';
aQueryBoth.ParamByName('vDataType').AsInteger := 1;

aQueryDataType.SQL.Text := 'SELECT * FROM myTable WHERE DataType = :vDataType';
...
aQueryDataType.ParamByName('vDataType').AsInteger := 1;