LEFt JOIN LATERAL 显示 SELECT 错误答案

【问题标题】：LEFt JOIN LATERAL showing error with SELECTLEFt JOIN LATERAL 显示 SELECT 错误
【发布时间】：2020-08-13 21:23:56
【问题描述】：

我正在尝试运行以下查询：

SELECT
tc.ID_NUMBER AS AFC_RPP_Number,
hc.BUSINESS AS Business,
hc.DIRECTOR AS Director,
tc.REASON_FOR_REVISION AS Description_of_Change
FROM alo_gg.AWS_PIM tc
left join lateral(
    select BUSINESS,DIRECTOR                
    FROM alo_ggg.tracker
    WHERE START_DATE <= tc.DATE AND  SO = tc.SO 
    ORDER BY START_DATE DESC 
    LIMIT 1
) hc;

以上查询显示错误：

ERROR:  syntax error at or near "SELECT"
left join lateral (SELECT BUSINESS,DIRECTOR...

如果我单独运行子查询，它会给我一个结果，但使用lateral 它会给我一个错误。

【问题讨论】：

@GMB 如果相关子查询没有产生行，那么主查询行也将被跳过。 LATERAL/LEFT JOIN LATERAL 不等价。
Greenplum 还是 Postgres？
使用Greenplum
我假设你想要CROSS JOIN LATERAL。另外，您能否edit 这个问题并直接从客户端添加 complete 错误消息？
Greenplum 不支持 LATERAL 连接

标签： sql greenplum lateral-join

【解决方案1】：

您需要添加ON TRUE并删除逗号：

SELECT
tc.ID_NUMBER AS AFC_RPP_Number,
hc.BUSINESS AS Business,
hc.DIRECTOR AS Director,
tc.REASON_FOR_REVISION AS Description_of_Change
FROM alo_gg.AWS_PIM tc -- removing comma
left join lateral(
    select BUSINESS,DIRECTOR                
    FROM alo_ggg.tracker
    WHERE START_DATE <= tc.DATE AND  SO = tc.SO 
    ORDER BY START_DATE DESC 
    LIMIT 1
) hc  ON TRUE;  -- adding `ON` clause

【讨论】：