合并 2 个 SELECT LEFT JOIN 查询，联合/声明 AS 不起作用 [英] Combine 2 SELECT LEFT JOIN queries, union/declaring AS not working

问题描述

我有这个 select 语句，它运行一个带有标题product_id"和一个值的单列.

I have this select statement, it runs a single column with heading 'product_id' and a value.

SELECT meta_value as product_id
FROM ctc_woocommerce_order_itemmeta
LEFT JOIN ctc_woocommerce_order_items ON ctc_woocommerce_order_itemmeta.order_item_id = ctc_woocommerce_order_items.order_item_id
WHERE meta_key = '_product_id'
AND order_id = 3988

我希望将结果与此声明结合起来:

I want the results to be combined with this statement:

SELECT meta_value as variation_id
FROM ctc_woocommerce_order_itemmeta
LEFT JOIN ctc_woocommerce_order_items ON ctc_woocommerce_order_itemmeta.order_item_id = ctc_woocommerce_order_items.order_item_id
WHERE meta_key = '_variation_id'
AND order_id = 3988

如何将两者结合起来?我试过 UNION，也试过类似下面的语句，但 phpMyAdmin 崩溃了.

How to combine the 2? I have tried UNION, also tried similar statement to below but phpMyAdmin crashes out.

SELECT x.a, y.b FROM (SELECT * from a) as x, (SELECT * FROM b) as y

我正在寻找 2 列的输出:

I am looking for output with 2 columns:

1 x product_id

1 x product_id

1 xvariation_id

1 x variation_id

推荐答案

我认为您在错误的地方编写了 SELECT.

I think you wrote the SELECTs in the wrong place.

SELECT (
  SELECT meta_value as product_id
  FROM ctc_woocommerce_order_itemmeta
  LEFT JOIN ctc_woocommerce_order_items ON ctc_woocommerce_order_itemmeta.order_item_id = ctc_woocommerce_order_items.order_item_id
  WHERE meta_key = '_product_id'
  AND order_id = 3988
) as product_id,
(
  SELECT meta_value as variation_id
  FROM ctc_woocommerce_order_itemmeta
  LEFT JOIN ctc_woocommerce_order_items ON ctc_woocommerce_order_itemmeta.order_item_id = ctc_woocommerce_order_items.order_item_id
  WHERE meta_key = '_variation_id'
  AND order_id = 3988
) as variation_id;

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