员工时间表回退?:

SELECT Table1.ID
    ,Table1.Date
    ,COALESCE(Table3.TimeIn, Table2.TimeIn) AS TimeIn
    ,COALESCE(Table3.TimeOut, Table2.TimeOut) AS TimeOut
FROM Table1
INNER JOIN Table2 -- Always have an expected schedule for an employee
    ON Table1.ID = Table2.ID
LEFT JOIN Table3 -- May.may not have an actual schedule for an employee
    ON Table3.ID = Table1.ID
    AND Table3.Date = Table1.Date
/*
ORDER BY Table1.ID
    ,Table1.Date
*/