Mysql Typs (Null) Typ (Integer)

[question]

Code:

QueryA.ParamByName('ID').AsInteger := QueryBID.AsInteger //this using the field of VCL Component)
QueryYA.ParamByName('ID').AsInteger :=  ueryB.FieldByName(('ID').AsInteger;// this using  sqil query fieldbyname

value of both query can be different, i mean Null and 0?

[Valle]

You can copy data without using Delphi:

Code:

-- untested, might need some more parenthesis
INSERT INTO `B` (foo, bar)
SELECT foo, bar FROM `A` WHERE id = 42;

That requires less network traffic and should be much faster.

Maybe that would be a better alternative for you.

[sx2008]

Zitat von question:

Code:

QueryA.ParamByName('ID').AsInteger := QueryBID.AsInteger //this using the field of VCL Component)
QueryYA.ParamByName('ID').AsInteger :=  ueryB.FieldByName(('ID').AsInteger;// this using  sqil query fieldbyname

If you want to transfer a Value that could be both a integer or NULL you have to use the data type "Variant".
A Variant can contain different data type like integer, floats, booleans, strings.
And a Variant can also be Null !
This means that Variant is a nullable data type.
To get or set the value of a field you can use the property Value .
The Properties AsString, AsInteger, AsBoolean,... are specialised properties.

Delphi-Quellcode:

// your code example using property Value instead of property AsInteger
QueryA.ParamByName('ID').Value := QueryBID.Value; //this using the field of VCL Component)
QueryYA.ParamByName('ID').Value :=  ueryB.FieldByName(('ID').Value;// this using  sqil query fieldbyname