Vb.net 我想检索字段中每个计数特定的数据

有没有办法做到这一点？我想检索字段中的每个数据计数

这是我的密码

 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

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有什么简单的方法可以做到这一点吗？

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

而不是

ExecuteScalar

来访问每一列：

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

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嗯..还有一件事..我们可以在sql中使用更新中的循环吗？@user3211476:您的第二个问题看起来不同，请先慢慢接受上面的答案。然后再问一个单独的问题。谢谢。嗯……如何接受答案？嗯..我的意思是..接受答案的按钮在哪里可以使这个问题成为已解决的..？@user3211476-单击答案左侧的勾号将其变为绿色，并将其标记为已接受。如果你认为答案是有用的，你也可以选择点击上箭头。