从SQL Server数据库获取数据

Question

寻找从数据库获取单个值的最简单方法。当你考虑使用.NET语言编写的所有9,000种方法时，这会让你感到困惑。 SqlCommands，DataReaders，Recordsets ...哦，我的！

假设我已经连接到打开的DB。我只是希望做这样的事情：

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，但我认为这将是这个样子在VB.Net：

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

试着这么做这个：

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