Question

他正在尝试使用多个嵌套的案例查询来构建SQL查询。

我的表格包含以下列：ID，UserId，EventInTime，InTime，EventOutTime，OutTime。

以下是困扰我的列的伪代码：

(If EventInTime ==0 then IT = InTime else IT = EventInTime;
If EventOutTime ==0 then IT = OutTime else OT = EventOutTime;
If IT or OT ==0 then 0 else OT-IT) as Suma

继承我的代码：

SELECT 
UserId, 
StatId, 
case when 
    case when EventInTime =0 
    then InTime 
    else EventInTime end=0 
    or 
        case when EventOutTime =0 
        then OutTime 
        else EventOutTime end 
        then 0
 else 
    case when EventOutTime =0 
    then OutTime 
    else EventOutTime end -
        case when EventInTime =0 
        then InTime 
        else EventInTime end 
        as suma
from Worktimes

我做错了什么？

Answer 1

缺少第二个内部CASE值零的比较：

if(userName.equals("")||password.equals("")||confirmPassword.equals(""))
            {
                Toast.makeText(getApplicationContext(), "Field Vacant", Toast.LENGTH_LONG).show();
                return;
            }
            // check if both password matches
            if(!password.equals(confirmPassword))
            {
                Toast.makeText(getApplicationContext(), "Password does not match", Toast.LENGTH_LONG).show();
                return;
            }
            else
            {
                // Save the Data in Database
                loginDataBaseAdapter.insertEntryrestau(userName, password);
                Toast.makeText(getApplicationContext(), "Account Successfully Created ", Toast.LENGTH_LONG).show();
                finish();
            }
        }

只有当两列都为零时，IT和OT才为零，因此前两个内部CASE可以简化：

SELECT UserId,
       StatId,
       CASE
       WHEN CASE EventInTime
            WHEN 0 THEN InTime
                   ELSE EventInTime
            END = 0
            OR
            CASE EventOutTime
            WHEN 0 THEN OutTime
                   ELSE EventOutTime
            END = 0                    -- !!!
       THEN 0
       ELSE CASE EventOutTime
            WHEN 0 THEN OutTime
                   ELSE EventOutTime
            END
            -
            CASE EventInTime
            WHEN 0 THEN InTime
                   ELSE EventInTime
            END
       END AS Suma
FROM Worktimes;

使查询更简单的另一种方法是将SELECT UserId, StatId, CASE WHEN (InTime = 0 AND EventInTime = 0) OR (OutTime = 0 AND EventOutTime = 0) THEN 0 ELSE CASE EventOutTime WHEN 0 THEN OutTime ELSE EventOutTime END - CASE EventInTime WHEN 0 THEN InTime ELSE EventInTime END END AS Suma FROM Worktimes;和IT作为虚拟列引入（这需要一个单独的子查询）：

OT

Sqlite嵌套案例查询

1 个答案: