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Daniel Dashkevich
Asked:2020-10-06 08:13:48 +0000 UTC2020-10-06 08:13:48 +0000 UTC

在 C# 中使用 CASE 进行数据库查询

  • 772

我正在尝试从数据库中卸载数据，但 CASE 语句不起作用，它给出的是空单元格而不是数据。在 SQLiteStudio 中，所有内容都通过此请求正确卸载。怎样成为？

conn = new SQLiteConnection(conn_string);
conn.Open();
SQLiteCommand command = new SQLiteCommand();
command.Connection = conn;
string query = "select count(id) as 'Всего заказов', case when status = 1 then count(id) else null end as 'Завершенных заказов', case when status = 1 then sum(cost) else null end as 'Прибыль' from appointment";
command.CommandText = query;

SQLiteDataAdapter da = new SQLiteDataAdapter(command);
dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource=dt;
conn.Close();
c#

2 个回答

  1. Best Answer
    select count(id) as 'Всего заказов',
  sum(case when status = 1 then 1 end) as 'Завершенных заказов',
  sum(case when status = 1 then cost end) as 'Прибыль'
from appointment
    • 1

  2. 当我在案例之后添加比较属性时，它起作用了。

    query = "select count(id) as 'Всего заказов', case status when status = 1 then count(id) else null end as 'Завершенных заказов', case status when status = 1 then sum(cost) else null end as 'Прибыль' from appointment";
    • 0

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