Question

寻找从数据库中获取单个值的最简单方法。当你考虑在.NET语言中存在的所有9,000种方法时，这会让人感到困惑。 SqlCommands，DataReaders，Recordsets ......哦，我的！

假设我已经打开了与数据库的连接。我只是想做这样的事情：

Dim age As Integer = <SQL statement here>

Answer 1

SqlConnection conn = new SqlConnection("connection string goes here");
SqlCommand cmd = new SqlCommand("SELECT foo FROM ...", conn);

conn.Open();
int age = (int)cmd.ExecuteScalar();
conn.Close();

不是VB.Net的人，但我认为它在VB.Net中看起来像这样：

Dim conn As SqlConnection = new SqlConnection("connection string goes here")
Dim cmd As SqlCommand = new SqlCommand("SELECT foo FROM ...", conn);

conn.Open()
Dim age As Integer = Convert.ToInt32(cmd.ExecuteScalar())
conn.Close()

Answer 2

尝试这样的事情：

Dim age As Integer=0
Using conn As New SqlClient.SqlConnection("YourConnectionString") 
    Using cmd As SqlClient.SqlCommand = conn.CreateCommand() 

        cmd.CommandText = "SELECT Age FROM Customer WHERE CustomerNumber = @CustNum" 
        cmd.Parameters.AddWithValue("@CustNum", SomeCustomerNumber) 
        conn.Open() 
        age = Convert.ToInt32(cmd.ExecuteScalar().ToString()) 

      End Using 
End Using

从SQL Server数据库获取数据

2 个答案: