Tài liệu Listing Tables in an Access Database ppt

[ Team LiB ] Recipe 10.14 Listing Tables in an Access Database Problem You need a list of all tables in your Access database. Solution Use the GetOLEDBSchemaTable( ) method of the OleDbConnection class or use ADOX through COM interop. The first technique uses the GetOLEDBSchemaTable( ) method to return schema information about user tables. These results are then displayed. For the second technique, you'll need a reference to the Primary Interop Assembly (PIA) for ADO provided in the file ADODB.DLL; select adodb from the .NET tab in Visual Studio .NET's Add Reference Dialog. You'll also need a reference to Microsoft ADO Ext. 2.7 for DDL and Security from the COM tab in Visual Studio .NET's Add Reference Dialog. The second technique creates an ADOX Catalog object through COM interop. The Tables property of this object accesses the collection of tables from which the name and other information are displayed. The C# code is shown in Example 10-14 . Example 10-14. File: ListAccessTablesForm.cs // Namespaces, variables, and constants using System; using System.Configuration; using System.Text; using System.Data; using System.Data.OleDb; // . . . // OLE DB StringBuilder result = new StringBuilder( ); // Open the OLE DB connection. OleDbConnection conn = new OleDbConnection( ConfigurationSettings.AppSettings["MsAccess_ConnectString"]); conn.Open( ); // Retrieve schema information for all tables. DataTable schemaTable = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] {null, null, null, "TABLE"}); result.Append("TABLE" + Environment.NewLine); // Iterate over the collection of table records. foreach(DataRow row in schemaTable.Rows) { result.Append(row["TABLE_NAME"] + Environment.NewLine); } conn.Close( ); resultTextBox.Text = result.ToString( ); // ADOX StringBuilder result = new StringBuilder( ); // Open the connection. ADODB.Connection conn = new ADODB.ConnectionClass( ); conn.Open(ConfigurationSettings.AppSettings["MsAccess_ConnectString"], "", "", 0); // Create an ADOX catalog object for the connecton. ADOX.Catalog cat = new ADOX.Catalog( ); cat.ActiveConnection = conn; result.Append("TABLE\tKEY" + Environment.NewLine); // Iterate over the collection of tables. foreach(ADOX.Table table in cat.Tables) { if(table.Type == "TABLE") { result.Append(table.Name + Environment.NewLine); // Iterate over the collection of keys for the table. foreach(ADOX.Key key in table.Keys) { result.Append("\t" + key.Name + " ("); // Iterate over the collection of columns for the key. foreach(ADOX.Column col in key.Columns) { result.Append(col.Name + ", "); } result.Remove(result.Length - 2, 2).Append(")" + Environment.NewLine); } result.Append(Environment.NewLine); } } cat = null; conn.Close( ); resultTextBox.Text = result.ToString( ); Discussion The solution shows two techniques that you can use to get a list of tables in an Access database. The first technique uses the GetOleDbSchemaTable( ) method of the OLE DB connection object. This technique is discussed in Recipe 10.2 . The second technique uses ActiveX Database Objects Extensions (ADOX) from COM interop. ADOX has a Tables property that exposes a collection of Table objects in the database. The user tables are determined by iterating over the collection of tables and selecting only those where Type property of the Table is TABLE. The Table object also exposes collections of Columns, Indexes, Keys, and Properties that can be used to further investigate the database. As an example, the sample code iterates over the collection of Keys in each table to get the list of both primary and foreign keys. [ Team LiB ] . [ Team LiB ] Recipe 10.14 Listing Tables in an Access Database Problem You need a list of all tables in your Access database. Solution Use the GetOLEDBSchemaTable(. ListAccessTablesForm.cs // Namespaces, variables, and constants using System; using System.Configuration; using System.Text; using System.Data; using