Question

有没有办法做到这一点？我想检索字段中的每个数据计数

这是我的代码..

 Dim cmd1 As New SqlCommand("SELECT COUNT(support) AS support " & _
                            "FROM   Studz_Table WHERE support ='others'",conn)
dim int1 as integer = cmd1.executescalar

Dim cmd2 As New SqlCommand("SELECT COUNT(support) AS support " & _
                            "FROM   Studz_Table WHERE support ='myself'",conn)
dim int2 as integer = cmd1.executescalar
Dim cmd3 As New SqlCommand("SELECT COUNT(support) AS support " & _
                            "FROM   Studz_Table WHERE support ='parent'",conn)
dim int3 as integer = cmd1.executescalar

有没有简单的方法可以做到这一点？

Answer 1

您可以使用SUM和CASE的组合来检索每种类型的计数。

Dim cmd As New SqlCommand("SELECT SUM(CASE WHEN support = 'others' THEN 1 ELSE 0 END) AS OthersCount, " & _
                          "SUM(CASE WHEN support = 'myself' THEN 1 ELSE 0 END) AS MyselfCount, " & _
                          "SUM(CASE WHEN support = 'parent' THEN 1 ELSE 0 END) AS ParentCount " & _
                            "FROM   Studz_Table WHERE support ='others'",conn)

您需要使用ExecuteReader代替ExecuteScalar来访问每列：

SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
     int int1 = reader[0];
     int int2 = reader[1];
     int int3 = reader[2];
}

我想检索字段中的每个计数特定数据

1 个答案: