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This article mainly explains "what is the ADO Connection object". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the ADO Connection object".

The ADO Connection object represents the * session of the data source. In the case of a client / server database system, this object can be equivalent to the actual network connection to the server. Some collections, methods, or properties of the ADO Connection object may be invalid.

You can use the collections, methods, and properties of the Connection object to configure the connection with the ConnectionString, ADO Connection object, and Mode properties before opening the connection. ConnectionString is the default property of the Connection object.

Set the CursorLocation property to invoke Cursor Service for OLE DB that supports batch updates. Use the DefaultDatabase property to set the default database for the connection. Use the ADO Connection object property to set the isolation level for transactions opened on the connection. Specify the OLE DB provider with the Provider property. Establish a physical connection to the data source with the Open method, and then disconnect with the Close method.

Use the Execute method to execute the command on the connection and configure the execution of the command with the properties of the ADO Connection object. Note that to execute the query without using the Command object, pass the query string to the Execute method of the Connection object. However, you need to use the Command object when you want to persist and re-execute the command text, or when you want to use query parameters.

Use the BeginTrans, CommitTrans, and RollbackTrans methods and the Attributes property to manage transactions on open connections, including nested transactions, if supported by the provider. Use the Errors collection to check for errors returned from the data source. Use the Version property to read the version used from the ADO Connection object.

Query records can use CRecordSet::Open () and CRecordSet::Requery () member functions. Before using the CRecordSet class object, you must use the CRecordSet::Open () function to obtain a valid recordset.

Once you have used the CRecordset::Open () function, you can use the CRecordSet::Requery () function for the next query.

When calling the CRecordSet::Open () function, if you have passed an open CDatabase object pointer to the m_pDatabase member variable of the CRecordset class object, then you can use the database object to establish an ODBC connection; otherwise (that is, m_pDatabase is a null pointer), you need to create a new ADO Connection object class object and connect it to the default data source, and then initialize the CRecordset class object. The default data source is obtained by the GetDefaultConnect () function.

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