過濾數據IF

Question

students(studentID PK, A, B,sec..) FeesStructure(feeStruct PK, feeA, feeB, ..) FeesCollected(FeesID PK,studentID FK,feeStruct FK, A,B,..)

如果students.sec = 'A' 返回FeesStructure.feeA，FeesCollected.A ..等 必須創建一個視圖，將返回基於一個如果數據。費用結構表有費用A，費用B ，只適用於學生的秒數。我需要根據students.sec返回feeA或feeB

Answer 1

您可以使用CASE：

select students.studentID, 
    case students.sec 
    when 'A' then FeesStructure.feeA 
    else FeesStructure.feeB 
    end as feesStructure, 
    case students.sec 
    when 'A' then FeesCollected.A 
    else FeesCollected.B 
    end as feesCollected 
from students, FeesStructure, FeesCollected 
where students.studentID=FeesStructure.studentID 
    and students.studentID=FeesCollected.studentID