MySQL中的十进制选择无效

Question

我试着在IBM书中执行一个问题的陈述，并给出了答案，但我说错了。

SELECT在此位置无效

SELECT LASTNAME, SALARY,
DECIMAL(SALARY*1.05,9,2) AS "INC-Y-SALARY",
DECIMAL(SALARY*1.05/12,9,2) AS "INC-M-SALARY"
FROM EMPLOYEE
WHERE SALARY*1.05 <= 20000
ORDER BY SALARY

将第二行和第三行替换为

SALARY*1.05 AS "INC-Y-SALARY",
SALARY*1.05/12 AS "INC-M-SALARY"

但是这个问题需要有两个小数位的列。

Answer 1

我找到了一个使用截断的解决方案。我之前不知道怎么用.

SELECT LASTNAME, SALARY,
TRUNCATE((SALARY*1.05),2) AS "INC-Y-SALARY",
TRUNCATE((SALARY*1.05/12),2) AS "INC-M-SALARY"
FROM EMPLOYEE
WHERE SALARY*1.05 <= 20000
ORDER BY SALARY;

谢谢你的帮助！

附带注意:我使用MySQL

Answer 2

你在找CAST()吗

SELECT LASTNAME, SALARY,
       CAST(SALARY*1.05 AS DECIMAL(9,2)) AS "INC-Y-SALARY",
       CAST(SALARY*1.05/12 AS DECIMAL(9,2)) AS "INC-M-SALARY"

这里是db<>fiddle。