sql - 一列中所有字段的总和

Question

我试图计算一列中所有数字的总和。

列名是整数类型的“单位”。

这应该有效吗？

cmd3 = New OleDbCommand("SELECT SUM(Units) FROM tblJobs WHERE BookedOut = NULL AND HoldDate = NULL ", con)

lblLiveUnits.Text = cmd3.ExecuteNonQuery()

谢谢

Answer 1

你的查询不正确，你不想做=NULL你应该使用的东西IS NULL：

SELECT SUM(Units)  As TotalUnits
FROM tblJobs 
WHERE BookedOut IS NULL 
  AND HoldDate IS NULL

然后在您的代码中，您将使用ExecuteScalar：

Int32 lblLiveUnits = 0;

cmd3 = New OleDbCommand("SELECT SUM(Units)  As TotalUnits FROM tblJobs WHERE BookedOut IS NULL AND HoldDate IS NULL ", con);

lblLiveUnits = cmd3.ExecuteScalar()