Excel表中的SQL查询

Posted 2021-03-28

我在Excel中的数据库中使用OleDbCommand运行查询，包含以下列：

name, city, inhabitants

我的代码：

 Cmd = new OleDbCommand();
 Cmd.Connection = Conn;
 Cmd.Parameters.AddWithValue("@city", city);
 Cmd.CommandText = "Select City, count(habitants) as h from [Sheet1$] where city = @city group by city";
 var Reader = await Cmd.ExecuteReaderAsync();

我收到此错误：

OleDbException：您尝试执行不包含指定表达式“city”的查询作为聚合函数的一部分。

如果它包含city列，为什么会出现此错误？

答案

您可以通过在查询中添加GROUP BY来解决此错误：

Cmd.CommandText = "Select City, count(habitants) as h from [Sheet1$] where city=@city group by City";

另一答案

使用FIRST()函数为city：

Cmd.CommandText = "SELECT FIRST(city) AS city, COUNT(habitants) AS h FROM [Sheet1$] WHERE city=@city GROUP BY city";