题解 | 更新员工信息表

WITH t1 AS(
SELECT
    employee_id,
    max(update_dt) UPDATE_DT
FROM EMPLOYEE_UPDATE
GROUP BY employee_id
)

SELECT
    t1.EMPLOYEE_ID,
    IF(t1.UPDATE_DT > ei.LAST_UPDATE_DT, eu.NEW_POSITION, ei.POSITION) POSITION,
    IF(t1.UPDATE_DT > ei.LAST_UPDATE_DT, t1.UPDATE_DT, ei.LAST_UPDATE_DT) LAST_UPDATE_DT
FROM t1
JOIN EMPLOYEE_INFO ei ON ei.employee_id = t1.employee_id
JOIN EMPLOYEE_UPDATE eu ON t1.employee_id = eu.employee_id AND t1.UPDATE_DT = eu.UPDATE_DT
ORDER BY t1.EMPLOYEE_ID