Clone data from one QSqlTableModel to new QSqlTableModel

Hasan Vaez

Hello guys,
I want to clone or copy from one Table to another one.
with the following codes they just refer to each other:

QSqlTableModel * OldModel = new QSqlTableModel(this);
OldModel->setTable(Program::DataBase::Definitions::TableName);
OldModel->setEditStrategy(QSqlTableModel::OnManualSubmit);
OldModel->select();

QSqlTableModel *NewModel = OldModel; (No error but this two object are same object. All refer to one place of memory)

If you change one, another will change.

Is there any solution to get a copy of rows/records/

Please do not suggest a deep copy in a FOR loop.

@Lifetime-Qt-Champion

Regards,

VRonin

Please do not suggest a deep copy in a FOR loop.

Then use QSqlQuery. It's just down to SQL. something like query->prepare("insert into newTable (select * from OldTable)"); query->exec();

If, however, you want a deep copy, you can use this library:

QSqlTableModel *NewModel = new QSqlTableModel(this);
NewModel ->setTable(Program::DataBase::Definitions::AnotherTableName);
NewModel ->setEditStrategy(QSqlTableModel::OnManualSubmit);
NewModel ->select();
BinaryModelSerialiser modelSerialiser(OldModel);
QByteArray deepCopyData;
modelSerialiser.saveModel(&deepCopyData);
modelSerialiser.setModel(NewModel);
modelSerialiser.loadModel(deepCopyData);

Hasan Vaez

@VRonin said in Clone data from one QSqlTableModel to new QSqlTableModel:

this library

Thank you VRonin for your prompt reply,
I do not test it yet, but there is a Recursive function with at least 10,000 time repeation. Every calling of function will run a FOR loop inside which load all 10,000 records. (10,000 time ^ 10,000 time) I use TableModel in the beginning of this function! Although this time is nothing for sweet QT(C++), but making query is very expensive. There should be codes just to copy a table to each other.
If I use a query or a deep copy guess how long it will take!

JonB

@Hasan-Vaez

I'm just going to say it: Given you are using SQL tables, are you sure your solution cannot be server-side SQL instead? You're talking about efficiency, and nothing you do client-side in Qt is going to be anywhere vaguely near what you will achieve server-side... This assumes the destination table is "permanent" at the server-side --- you don't actually say what this copying is for.

Also, if you stick to client-side copying, I don't know where you get your statements/calculations from:

FOR loop inside which load all 10,000 records

If you're copying elements from one table to another manually, it will only be in-memory, there will be no "loading [from database]" if that's what you mean?

(10,000 time ^ 10,000 time)

What does this mean? 10K to the power of 10K ?? If you are copying 10K records, you will do 9approx) 10K reads + 10K writes == O(20K).