Question

我需要选择数据，最后我需要将date_payment更改为DateTime到Text，请帮助...

我写这个查询

SELECT r.id, user_name, user_phone, date_create, REPLACE( date_payment,  '0000-00-00 00:00:00',  'No payment' ) , payment_method, amount, rs.name_ru
FROM request AS r, request_status AS rs
WHERE r.status = rs.id
LIMIT 0 , 30

在SQL控制台查询中

是有效的，date_payment将被重播，但是：

MySqlCommand cmd = new MySqlCommand(query, conn);

        dt.Load(cmd.ExecuteReader());

        GetList();

        source.DataSource = dt;
dataGrid1.ItemsSource = source;

然后datagrid中的列（date_payment）为空 - 为什么？

Answer 1

您计算的列没有任何名称。添加“AS updated_date_payment”关键字并在您的计划中请求“updated_date_payment”列：

SELECT r.id, user_name, user_phone, date_create, REPLACE( date_payment,  '0000-00-00 00:00:00',  'No payment' ) AS updated_date_payment, payment_method, amount, rs.name_ru
FROM request AS r, request_status AS rs
WHERE r.status = rs.id
LIMIT 0 , 30

Answer 2

使用以下代码：

SELECT r.id, user_name, user_phone, date_create, REPLACE( date_payment,  '0000-00-00 00:00:00',  'No payment' ) AS date_payment, payment_method, amount, rs.name_ru
FROM request AS r, request_status AS rs
WHERE r.status = rs.id
LIMIT 0 , 30

您必须使用 AS 关键字。否则，它将返回* REPLACE（date_payment，'0000-00-00 00：00：00'，'无付款'）*的列名称为（无列名称）

触发sql（更改类型列）

2 个答案: