ADO 记录集不返回任何内容

Question

我正在使用 ADO Recorset 访问 MySQL 表，但是 ADO Recordset 不返回记录。我在 Visual Studio 中使用 VB.NET。我可以通过连接对象（如下）与数据库建立通信，建立连接，创建表，但是在通过 Recordset 返回信息时，会出错。

Dim conn As New ADODB.Connection
Dim rs As New ADODB.Recordset
Dim fld As ADODB.Field
Dim aux As String

aux = "Provider = MSDASQL;Driver={MySQL ODBC 5.2 ANSI Driver}; Server=localhost; Database = db-teste; User=root; Password=123456; Option=3;"
conn.Open(aux)

'create table
conn.Execute("DROP TABLE IF EXISTS my_ado")
conn.Execute("CREATE TABLE my_ado(id int Not null primary key, name varchar(20)," &
                "txt text, dt date, tm time, ts timestamp)")
'insert
conn.Execute("INSERT INTO my_ado(id,name,txt) values(1,100,'venu')")
conn.Execute("INSERT INTO my_ado(id,name,txt) values(2,200,'MySQL')")

'============================================================================
' UNTIL HERE, IT WORKS FINE!
'============================================================================


' This does not get anything
rs.Open("SELECT * FROM my_ado", conn)
rs.MoveFirst()

' RecordCount always returns "-1" <<<<<<====================
Debug.Print(Str(rs.RecordCount()))

' rs.Fields = ERROR
For Each fld In rs.Fields 
    Debug.Print(fld.Name)
Next

怎么了？

Answer 1

检查数据库配置，确保AUTO COMMIT开关打开，否则需要提交数据。我对 MySQL 并不完全熟悉，但我知道 INSERT 需要以一种或另一种方式提交。

这篇文章解释了一切：

https://dba.stackexchange.com/questions/4252/do-inserts-get-auto-committed

将此添加到您的代码中 rs.Open("SELECT * FROM my_ado", conn) 代码行之后：

' Create dataset and data adapter objects
Dim ds As New DataSet("Recordset")
Dim da As New OleDbDataAdapter()

' Call data adapter's Fill method to fill data from ADO
' Recordset to the dataset

da.Fill(ds, rs, "Data")

数据应该在ds.Tables!Data，你可以用这一行检查：

ds.Tables!Data.Rows.Count