如何把数据库中一个字段提取到一个指定的变量中？

Question

Public Sub ReadMyData(myConnString As String)
    Dim mySelectQuery As String = "SELECT OrderID, CustomerID FROM Orders"
    Dim myConnection As New SqlConnection(myConnString)
    Dim myCommand As New SqlCommand(mySelectQuery, myConnection)
    myConnection.Open()
    Dim myReader As SqlDataReader
    myReader = myCommand.ExecuteReader()
    ' Always call Read before accessing data.
    While myReader.Read()
        Console.WriteLine((myReader.GetInt32(0) & ", " & myReader.GetString(1)))
    End While
    ' always call Close when done reading.
    myReader.Close()
    ' Close the connection when done with it.
    myConnection.Close()
End Sub 'ReadMyData

Answer 1

晕..一贴贴这么多??提取记录你可以用DataSet或OleDbDataReader
OleDbCommand cmd = new OleDbCommand("select a,b,c from tb",Conn)
OleDbDataReader rad = cmd.ExecuteReader();string a = rad["a"].ToString();
string b = rad["b"].ToString();
string c = rad["c"].ToString();

Answer 2

Dim SQL As String = "SELECT * FROM Table"
Dim SqlDa As SqlDataAdapter = New SqlDataAdapter(SQL, Connection)
Dim oDs as New DataSet()
SqlDa.Fill(oDs)
oDs.Tables(0).Rows(0)(0)

Answer 3

//加载记录从数据库
OleDbConnection myConn=new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\CSharp3\QXKMeTone\bin\Debug\First.mdb;");
myConn.Open();
OleDbDataAdapter thisAdapter= new OleDbDataAdapter("SELECT * FROM Student",myConn);
OleDbCommandBuilder thisBuilder=new OleDbCommandBuilder(thisAdapter);
DataSet thisDataSet=new DataSet();
thisAdapter.Fill(thisDataSet,tablename);
int nTotals=thisDataSet.Tables[tablename].Rows.Count;
Student student=new Student();
for(int i=0;i<nTotals;i++)
{
student.Name=(string)thisDataSet.Tables[tablename].Rows[i]["name"];
student.Sex=(bool)thisDataSet.Tables[tablename].Rows[i]["sex"];
student.Folk=(string)thisDataSet.Tables[tablename].Rows[i]["folk"];
student.Address=(string)thisDataSet.Tables[tablename].Rows[i]["address"];
student.Telephone=(string)thisDataSet.Tables[tablename].Rows[i]["telephone"];
student.Nativeplace=(string)thisDataSet.Tables[tablename].Rows[i]["nativeplace"];
student.Intogroup=(DateTime)thisDataSet.Tables[tablename].Rows[i]["intogroup"];
student.Intoband=(DateTime)thisDataSet.Tables[tablename].Rows[i]["intoband"];
student.Fromschool=(string)thisDataSet.Tables[tablename].Rows[i]["fromschool"];
student.Suspend=(DateTime)thisDataSet.Tables[tablename].Rows[i]["suspend"];
student.IntoDate=(DateTime)thisDataSet.Tables[tablename].Rows[i]["intoDate"];
student.ReapDate=(DateTime)thisDataSet.Tables[tablename].Rows[i]["reapDate"];
student.Intoschool=(DateTime)thisDataSet.Tables[tablename].Rows[i]["intoschool"];
student.Serial=(int)thisDataSet.Tables[tablename].Rows[i]["serial"];
student.Borndate=(DateTime)thisDataSet.Tables[tablename].Rows[i]["borndate"];
student.Polity=(string)thisDataSet.Tables[tablename].Rows[i]["polity"];
student.IDCard=(string)thisDataSet.Tables[tablename].Rows[i]["iDCard"];
student.Intogroupaddr=(string)thisDataSet.Tables[tablename].Rows[i]["intogroupaddr"];
student.Intobandaddr=(string)thisDataSet.Tables[tablename].Rows[i]["intobandaddr"];
student.Borndate=(DateTime)thisDataSet.Tables[tablename].Rows[i]["borndate"];
students.Add(student);
}
myConn.Close();

Answer 4

我在大头的时候发的这个问题
大家Happy吧