使用 JOOQ 的日期时间字段按日期分组

Question

我有一个名为 delivery 的 table 和日期时间字段 delivery_time。

+--------------------+------------------------------------------+------+-----+-------------------+
| Field              | Type                                     | Null | Key | Default           |
+--------------------+------------------------------------------+------+-----+-------------------+
| delivery_time      | datetime                                 | YES  |     | NULL              |

我想统计每个日期的送货情况。使用普通 sql 我可以做到这一点

select  CAST(delivery_time as DATE) as date, count(*) as count from delivery group by CAST(delivery_time as DATE);

+------------+-------+
| date       | count |
+------------+-------+
| 2021-04-21 |     1 |
| 2021-03-22 |    11 |
| NULL       |     3 |
| 2021-03-21 |     1 |
| 2021-04-22 |     2 |
| 2021-04-30 |     1 |
+------------+-------+

但是当我尝试使用 JOOQ 执行此操作时，它无法正常工作（仅返回空行）

jooq.dsl()
.select(
        date(Tables.DELIVERY.DELIVERY_TIME.toString()),
        count()
)
.from(Tables.DELIVERY)
.groupBy(date(Tables.DELIVERY.DELIVERY_TIME.toString()))
.fetch()

谁能帮我用 jooq 写这个查询

Answer 1

您正在使用 Object.toString() method, which is available on all Java objects for debugging purposes. In jOOQ, you're going to get a string representation of your column expression. There's no point in doing that in your case. Just use the DSL.cast() 方法，就像您使用 SQL 一样。

假设通常的静态导入：

import static org.jooq.impl.DSL.*;
import static org.jooq.impl.SQLDataType.*;
import static com.example.Tables.*;

写

jooq.dsl()
    .select(cast(DELIVERY.DELIVERY_TIME, DATE), count())
    .from(DELIVERY)
    .groupBy(cast(DELIVERY.DELIVERY_TIME, DATE))
    .fetch();

使用 JOOQ 的日期时间字段按日期分组

Group by date using a datetime field with JOOQ

mysql

jooq