你可以使用已经存在的数据库或则创建一个你自己的数据库。ADO自身不能提供创建数据库的方法。你可以使用Microsoft ActiveX Data Objects Extensionsf or Data Definition Language and Security,简称ADOX来创建。在使用ADOX前，你必须参考你的项目，在Visual C++ Express的主菜单中，你可以点击, Project -> References... 右键点击项目名，点参考
在属性页，点新增 在COM页，指定 Microsoft ADO Ext. 2.7 or 2.8 for DDL and Security:
After referencing the library, you can use its classes. The classes of the ADOX library are stored in a namespace named ADOX.
The Catalog Class
To create and manage various objects of a database, the ADOX namespace provides an interface named Catalog and its derived class named CatalogClass. To use this class, you can first declare a handle to it. Here is an example:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX;
}
After declaring the class, you can initialize it using the New operator:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX;
catADOX = gcnew ADOX::Catalog;
}
Database Creation
The Connection String of the Catalog
To support database creation, the Catalog interface (or the CatalogClass class is equipped with the Create() method. Its syntax is:
System::Object ^ Create(System::String ^ ConnectionString)
The Create() method takes one argument referred to as the connection string. This string is made of sections separated by semi-colons. The formula used by these sections is:
Key1=Value1;Key2=Value2;Key_n=Value_n;
The first part of the connection string is called the provider. It is software that handles the database. To specify it, assign the desired name to the provider key. Here is an example:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX = gcnew ADOX::Catalog;
catADOX->Create(L"Provider=");
}
There are various providers in the database industry. One of them is Microsoft SQL Server and it is represented by SQLOLEDB. If you want to create a Microsoft SQL Server database, specify this provider. Here is an example:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX = gcnew ADOX::Catalog;
catADOX->Create(L"Provider=Microsoft.JET.OLEDB.4.0");
}
When creating this type of database, there are some other pieces of information you must provide in the connection string. Another provider is the Microsoft JET database engine represented as Microsoft.JET.OLEDB.4.0. To create a database for it, specify its provider accordingly. Here is an example:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX = gcnew ADOX::Catalog;
catADOX->Create(L"Provider=Microsoft.JET.OLEDB.4.0");
}
You can also include the name of the provider as its own string. To do that, you can include it in single-quotes:
Private Sub btnCreateDatabase_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnCreateDatabase.Click
' Using the Catalog class of the ADOX namespace
Dim catADOX As ADOX.Catalog = New ADOX.Catalog
catADOX.Create("Provider='Microsoft.Jet.OLEDB.4.0'"
End Sub
If you are creating a database, the second part of the connection string can be used to specify the path and the name of the database. This section must start with the Data Source key and assigned the path that consists of the drive and the folder(s). After the last folder, the name of the database must have the .mdb extension. For example, to create a database called Exercise that would reside in a folder called Exercises of the C: drive, you can specify the connection string as follows:
System::Void btnCreateDatabase_Click(System::Object^ sender, System::EventArgs^ e)
{
ADOX::Catalog ^ catADOX = gcnew ADOX::Catalog;
catADOX->Create(L"Provider='Microsoft.JET.OLEDB.4.0';" +
"Data Source=C:\\Programs\\Exercise1.mdb");
}
You can also include the value of the Data Source key in single-quotes.
Instead of directly passing a string to the Create() method, you can first declare a String variable, initialize it with the necessary provider/data source, and then pass that string variable to the Create() method.