Php MySQL 5.5大小写语法不正确

嘿，我不能让这个case语句工作，有人介意告诉我语法有什么问题吗

SELECT standards.standard_id, standards.title, standards.level,standards.credits, SUM(standards.credits), standards.assessment 

CASE  WHEN standards.assessment = 1 THEN 'External' ELSE 'Internal' END CASE
FROM standards JOIN courses_standards ON standards.standard_id = courses_standards.standard_id 
WHERE courses_standards.course_id = 1

确切的错误是：

1064-您的SQL语法有错误；检查与您的MySQL服务器版本对应的手册，了解在第3行的“CASE WHEN standards.assessment=1，然后是“External”ELSE“Internal”END CASE FR”附近使用的正确语法

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您结束案例的方式存在语法错误。您需要在结束案例时提供别名

SELECT standards.standard_id, standards.title, standards.level,standards.credits, SUM(    standards.credits), standards.assessment, 

CASE  WHEN standards.assessment = 1 THEN 'External' ELSE 'Internal' END assessment
FROM standards JOIN courses_standards ON standards.standard_id = courses_standards.    standard_id 
WHERE courses_standards.course_id = 1

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您遗漏了

标准之间的逗号。评估

和

案例

这些是基本错误。缺少逗号，大小写是保留字，没有GROUPBY子句