ADO stands for ActiveX Data Objects and is a set of software components that provide access to data stored in different formats and in different data sources. The Microsoft Data Access Components (MDAC) provide the interface between the data and the applications that use it. ADO is an integral part of the MDAC and provides a simple, high-level interface for accessing data.
The main benefit of using ADO is that it makes it easier to access data from different data sources. This is because the interface is designed to be simple and consistent, regardless of the underlying data source. For example, the same code can be used to access data from a Microsoft Access database as from a SQL Server database.
ADO also makes it easier to manipulate data. For example, it is possible to insert, update and delete data using a single piece of code, which is much simpler than writing multiple statements for each operation. This makes it easier to write and maintain code, as well as making the code more efficient.
Finally, ADO provides a number of features that make it easier to work with data, such as transactions and connection pooling. Transactions enable changes to be made to multiple databases at the same time, while connection pooling improves the performance of applications by reusing existing connections to databases.
ADO is made up of several components, each of which performs a specific task. These components are:
- Connection: This component is used to connect to a data source.
- Recordset: This component is used to store and manipulate data from a data source.
- Command: This component is used to execute commands on a data source, such as SQL statements.
- Parameter: This component is used to pass parameters to a command.
- Error: This component is used to handle errors that occur when working with data.
To use ADO, you need to have the Microsoft Data Access Components (MDAC) installed. You can then use the components to connect to a data source and execute queries and other commands. For example, to connect to a Microsoft Access database, you would use the following code:
Dim cn As ADODB.Connection
Set cn = New ADODB.Connection
cn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydatabase.mdb"
Once the connection is open, you can then execute commands on the data source. For example, to execute a SQL query, you would use the following code:
Dim cmd As ADODB.Command
Set cmd = New ADODB.Command
cmd.ActiveConnection = cn
cmd.CommandText = "SELECT * FROM MyTable"
The code above creates a new Command object and sets the connection to the open connection. The command text is then set to the SQL query and the Execute method is called to execute the query. The results of the query can then be retrieved from the Command object.
ADO is a powerful set of components that makes it easier to access and manipulate data from different data sources. The components are easy to use and provide a consistent interface for working with data. By using ADO, you can simplify your code and make it more efficient.