Question

我打算运行一个查询，在提供admission_code时提供最新的欠款，但是存在一些逻辑错误：

SELECT * 
FROM fees_invoice_information AS fii
WHERE fii.admission_code = 12111

此SQL返回：

enter image description here

当我想从以下查询中获取最新记录时

SELECT
    MAX(fii.id),fii.*,
    sep.registration_code,
    sep.admission_code,
    fii.arrears,
    sep.is_enabled 
FROM 
    fees_invoice_information AS fii
JOIN 
    std_education_profile AS sep ON fii.admission_code = sep.admission_code 
WHERE 
    fii.`admission_code`  = 12111

我明白了：

enter image description here

其中＆＃34;欠款＆＃34;列不是＆＃39; 0＆＃39;

Answer 1

将MAX条件移至WHERE子句中的子查询：

SELECT fii.*,
       sep.registration_code,
       sep.admission_code,
       sep.is_enabled 
FROM fees_invoice_information AS fii
INNER JOIN std_education_profile AS sep
    ON fii.admission_code = sep.admission_code 
WHERE fii.admission_code = 12111 AND
      fii.id = (SELECT MAX(id) FROM fees_invoice_information)

或者你可以使用LIMIT 1技巧：

SELECT fii.*,
       sep.registration_code,
       sep.admission_code,
       sep.is_enabled 
FROM fees_invoice_information AS fii
INNER JOIN std_education_profile AS sep
    ON fii.admission_code = sep.admission_code 
WHERE fii.admission_code = 12111
ORDER BY fii.id DESC
LIMIT 1

注意：这假定根据最大ID仅返回单个记录是合乎逻辑的。如果连接不是一对一，那么您可能希望返回记录的组或一组记录的聚合。

两个SQL查询返回奇数结果

1 个答案: