当我在哪里不工作时使用date_add，为什么？

Question

SELECT * 
FROM PATIENT 
WHERE PATIENTNUM = (SELECT PATIENTNUM 
        FROM CONSULTATION 
        WHERE CONSULTATIONDATE = 
        (SELECT DATE_ADD(curdate(), INTERVAL 1 DAY) AS DAYTOM); 

这是行不通的。

但是，当我只插入这个

SELECT DATE_ADD(curdate(), INTERVAL 1 DAY) AS DAYTOM 

其工作...

为什么？

Answer 1

我认为正确的做法是

SELECT * 
    FROM PATIENT 
    WHERE PATIENTNUM IN (SELECT PATIENTNUM 
       FROM CONSULTATION 
       WHERE CONSULTATIONDATE IN (SELECT DATE_ADD(curdate(), INTERVAL 1 DAY)    AS DAYTOM)); 

Answer 2

您错过了一个支架？

SELECT * 
FROM PATIENT 
WHERE PATIENTNUM = (SELECT PATIENTNUM 
        FROM CONSULTATION 
        WHERE CONSULTATIONDATE = (SELECT DATE_ADD(curdate(), INTERVAL 1 DAY) AS DAYTOM));