ADO对象和集合

ADO中一共提供了九个对象和四个集合

对象、集合	描述
Connection object	代表了与数据源的唯一会话，即已经打开的、与数据源的连接。
Command object	Command对象定义了将对数据源执行的命令；
Recordset object	可用来存储一个TABLE中所有的记录，也用来存储某个命令的执行结果，如一个查询语句的执行结果。整个Recordset 对象由records (rows)和fields (columns)组成.
Record object	代表某一行的数据（也就是用来表示一个record）
Stream object	代表一个二进制或者文本数据流；
Parameter object(和参数化的查询过程相关)	代表一个与Command对象相关的参数或者变量；该Command对象是基于参数化查询或存贮的过程。
Field object	代表一列数据
Property object	代表ADO的某一特性；具体依赖于提供者；
Error object	某一次操作的所产生的错误的详细的信息
Fields collection	Contains all the Field objects of a Recordset or Record object.
Properties collection	Contains all the Property objects for a specific instance of an object.
Parameters collection	Contains all the Parameter objects of a Command object.
Errors collection	Contains all the Error objects created in response to a single provider-related failure.

下面贴出MSDN中所给出的一段VB代码，用以说明几个基本对象的作用，不懂VB没关系，我加了一部分注释。

' Define a Connection object
 Dim oConn As ADODB.Connection

 ' Define a Recordset object
Dim oRs As ADODB.Recordset

' Define a String object used to set the property of Connection object
Dim sConn As String

' Define a String object used to store SQL query command
Dim sSQL as String

' Set the ConnectionString property
sConn = "Provider='SQLOLEDB';Data Source='MySqlServer';" & _
          "Initial Catalog='Northwind';Integrated Security='SSPI';"

' Open a connection.
Set oConn = New ADODB.Connection
oConn.Open sConn

' Make a query over the connection.
' &_ is used to indicate that the next line is a continuation of the previous line
sSQL = "SELECT ProductID, ProductName, CategoryID, UnitPrice " & _
             "FROM Products"

' execute the query command
Set oRs = New ADODB.Recordset
oRs.Open sSQL, oConn, adOpenStatic, adLockBatchOptimistic, adCmdText
                      
MsgBox oRs.RecordCount
        
' Close the connection.
oConn.Close
Set oConn = Nothing