mysql - 在 INNER JOIN 中使用列别名

Question

尝试运行以下查询时，我收到错误“'on Clause' 中的未知列 'YahrzeitName'”:

SELECT 
concat(yahrzeit.firstName, ' ', yahrzeit.middleName, ' ', yahrzeit.lastName) 
AS 'YahrzeitName', 

concat(yahrzeit.gregorianYear, '-', yahrzeit.gregorianMonthNum, '-', yahrzeit.gregorianDay) 
AS Date,

tbldecedent.Name

FROM yahrzeit INNER JOIN tbldecedent 
ON YahrzeitName = tbldecedent.Name

Answer 1

您不能在 join 语句中使用列别名，请用完整表达式替换别名:

SELECT 
    concat(yahrzeit.firstName, ' ', yahrzeit.middleName, ' ', yahrzeit.lastName) AS `YahrzeitName`,
    concat(yahrzeit.gregorianYear, '-', yahrzeit.gregorianMonthNum, '-', yahrzeit.gregorianDay) AS `Date`,
    tbldecedent.Name
FROM yahrzeit 
INNER JOIN tbldecedent
ON concat(yahrzeit.firstName, ' ', yahrzeit.middleName, ' ', yahrzeit.lastName) = tbldecedent.Name