MySQL案例语句无法识别的关键字&；意外标记

我不知道为什么我在MySQL查询中从第一个

CASE

关键字开始的每一个单词都有错误，我希望有人能看到我过去几个小时绞尽脑汁的东西。下面是一个经过裁剪的代码示例：

CREATE TEMPORARY TABLE low_revenue_a ENGINE=MEMORY AS
(SELECT fielda,fieldb,
CASE WHEN quality_rev = 'A' THEN 1 WHEN quality_rev = 'B' THEN 2 WHEN quality_rev = 'C' THEN 3 END AS quality_rev,
fieldc,fieldd,
CASE WHEN quality_sales = 'A' THEN 1 WHEN quality_sales = 'B' THEN 2 WHEN quality_sales = 'C' THEN 3 END AS quality_sales,
fielde,fieldf,
CASE WHEN quality_other_sales = 'A' THEN 1 WHEN quality_other_sales = 'B' THEN 2 WHEN quality_other_sales = 'C' THEN 3 END AS quality_other_sales,
fieldg,fieldh,myyear
FROM Db.mytable
WHERE myyear = 2014);

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一旦我添加了

CASE

语句，所有意外的标记和无法识别的关键字错误都会出现。有什么想法吗？

这会产生同样的错误吗

CREATE TEMPORARY TABLE low_revenue_a ENGINE=MEMORY AS
    SELECT fielda, fieldb,
           (CASE WHEN quality_rev = 'A' THEN 1
                 WHEN quality_rev = 'B' THEN 2 
                 WHEN quality_rev = 'C' THEN 3
            END) AS quality_rev,
           fieldc, fieldd,
           (CASE WHEN quality_sales = 'A' THEN 1
                 WHEN quality_sales = 'B' THEN 2
                 WHEN quality_sales = 'C' THEN 3
            END) AS quality_sales,
           fielde, fieldf,
           (CASE WHEN quality_other_sales = 'A' THEN 1
                 WHEN quality_other_sales = 'B' THEN 2
                 WHEN quality_other_sales = 'C' THEN 3
            END) AS quality_other_sales,
           fieldg, fieldh, myyear
    FROM Db.mytable
    WHERE myyear = 2014;

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我遇到的问题有两个方面。第一，括号确实帮助并消除了phpmyadmin中显示的错误。另一个原因是我自己愚蠢的疏忽，因为我拼错了一个字段名：quality_rev。非常感谢！不管怎样，你的建议对我收到过多的错误起了作用。