如何将 MySQL 语法 WITH `cte` AS (VALUES ROW(1), ROW(2), ROW(n)) 转换为 jOOQ DSL？

Posted 2023-03-28

【中文标题】如何将 MySQL 语法 WITH `cte` AS (VALUES ROW(1), ROW(2), ROW(n)) 转换为 jOOQ DSL？

【英文标题】：How convert MySQL syntax WITH `cte` AS (VALUES ROW(1), ROW(2), ROW(n)) to jOOQ DSL?

【发布时间】：2021-10-08 22:18:49

【问题描述】：

我有一个 mysql 的 SQL：

WITH `cte` AS (
    ( SELECT 1431655747 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 1431655733 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827794 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827865 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 1073741809 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 1073741759 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827800 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 1431655693 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827789 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827838 AS `n` FROM DUAL ) UNION ALL
    ( SELECT 715827823 AS `n` FROM DUAL ) UNION ALL
( SELECT 858993391 AS `n` FROM DUAL )) SELECT
`cte`.`n`,
`maxmind_country`.`country`.`name_en` 
FROM
    `cte`
    JOIN `maxmind_country`.`ipv4` ON `cte`.`n` BETWEEN `maxmind_country`.`ipv4`.`start_int` 
    AND `maxmind_country`.`ipv4`.`last_int`
    JOIN `maxmind_country`.`country` ON `maxmind_country`.`country`.`geoname_id` = `maxmind_country`.`ipv4`.`v_geoname_id`;

转换为 jOOQ DSL 后：

String ipAlias = "n";
SelectSelectStep<Record1<UInteger>> unionIps = ips
    .stream()
    .distinct()
    .map(value -> DSL.select(DSL.val(value).as(ipAlias)))
    .reduce((r1, r2) -> (SelectSelectStep<Record1<UInteger>>) r1.unionAll(r2))
    .orElse(null);

if(unionIps == null)
    return null;

CommonTableExpression<Record1<UInteger>> cte = DSL.name("cte").as(unionIps);
Field<UInteger> ipField = cte.field(ipAlias, UInteger.class);
return dslContext
    .with(cte)
    .select(ipField, COUNTRY.NAME_EN)
    .from(cte)
    .join(IPV4).on(ipField.between(IPV4.START_INT, IPV4.LAST_INT))
    .join(COUNTRY).on(COUNTRY.GEONAME_ID.eq(IPV4.V_GEONAME_ID))
    .fetchMap(ipField, Country.class);

结果将是：

+------------+----------------+
| n          | name_en        |
+------------+----------------+
| 1431655747 | Spain          |
| 1431655733 | Spain          |
|  715827794 | China          |
|  715827865 | China          |
| 1073741809 | United States  |
| 1073741759 | United States  |
|  715827800 | China          |
| 1431655693 | Spain          |
|  715827789 | China          |
|  715827838 | China          |
|  715827823 | China          |
|  858993391 | United Kingdom |
+------------+----------------+
12 rows in set (0.16 sec)

但是解释显示了一个多余的UNION：

id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1   PRIMARY <derived2>      ALL                 12  100,00  
1   PRIMARY ipv4        ALL ipv4_start_int_UNIQUE,ipv4_last_int_UNIQUE,ipv4_v_geoname_id_fk_idx             325934  11,11   Range checked for each record (index map: 0x7)
1   PRIMARY country     eq_ref  PRIMARY PRIMARY 4   maxmind_country.ipv4.v_geoname_id   1   100,00  
2   DERIVED                                     No tables used
3   UNION                                       No tables used
4   UNION                                       No tables used
5   UNION                                       No tables used
6   UNION                                       No tables used
7   UNION                                       No tables used
8   UNION                                       No tables used
9   UNION                                       No tables used
10  UNION                                       No tables used
11  UNION                                       No tables used
12  UNION                                       No tables used
13  UNION                                       No tables used

我用另一种 MySQL 语法重写了一个 SQL - VALUES ROW(1)、ROW(2)、ROW(n)：

WITH `cte` AS (
VALUES ROW(1431655747),
    ROW(1431655733),
    ROW(715827794),
    ROW(715827865),
    ROW(1073741809),
    ROW(1073741759),
    ROW(715827800),
    ROW(1431655693),
    ROW(715827789),
    ROW(715827838),
    ROW(715827823),
    ROW(858993391)) SELECT
`cte`.`column_0`,
`maxmind_country`.`country`.`name_en` 
FROM
    `cte`
    JOIN `maxmind_country`.`ipv4` ON `cte`.`column_0` BETWEEN `maxmind_country`.`ipv4`.`start_int` 
    AND `maxmind_country`.`ipv4`.`last_int`
    JOIN `maxmind_country`.`country` ON `maxmind_country`.`country`.`geoname_id` = `maxmind_country`.`ipv4`.`v_geoname_id`;

结果相同：

+------------+----------------+
| column_0   | name_en        |
+------------+----------------+
| 1431655747 | Spain          |
| 1431655733 | Spain          |
|  715827794 | China          |
|  715827865 | China          |
| 1073741809 | United States  |
| 1073741759 | United States  |
|  715827800 | China          |
| 1431655693 | Spain          |
|  715827789 | China          |
|  715827838 | China          |
|  715827823 | China          |
|  858993391 | United Kingdom |
+------------+----------------+
12 rows in set (0.16 sec)

但是规划器不使用UNION的：

id select_type table partitions type possible_keys key key_len ref rows filtered Extra
1   PRIMARY <derived2>      ALL                 12  100,00  
1   PRIMARY ipv4        ALL ipv4_start_int_UNIQUE,ipv4_last_int_UNIQUE,ipv4_v_geoname_id_fk_idx             325934  11,11   Range checked for each record (index map: 0x7)
1   PRIMARY country     eq_ref  PRIMARY PRIMARY 4   maxmind_country.ipv4.v_geoname_id   1   100,00  
2   DERIVED                                     No tables used

问题：如何将最后一个脚本转换为 jOOQ DSL？我没有找到任何方法

WITH `cte` AS (VALUES ROW(1), ROW(2), ROW(n)) ... ?

【问题讨论】：

为什么你认为解释中的工会有问题？

【参考方案1】：

从 jOOQ 3.15 开始，还没有办法将 standard SQL VALUES constructor 表示为 org.jooq.Select。它只能表示为org.jooq.Table，参见：https://github.com/jOOQ/jOOQ/issues/5871。

因此，您还不能使用 jOOQ DSL 来表示所需的确切语法，但您可以在 FROM 子句中使用 VALUES：

selectFrom(values(...))

这应该会产生与您正在寻找的计划几乎相同的计划。另一种解决方法是使用plain SQL templating