-- =====================================================
-- 初始化 SignUp 表的序號 (SeqNo) 
-- 用途：為現有的參加人員記錄補充序號
-- 說明：按活動(CourseID)和ID排序，為每個活動內的參加人員自動編號
-- =====================================================

-- 方式一：使用 ROW_NUMBER() - 推薦（支援 SQL Server 2005+）
-- 此方式會為每個活動內的記錄按 ID 順序編號

BEGIN TRANSACTION;

UPDATE SignUp
SET SeqNo = rn.RowNum
FROM SignUp su
INNER JOIN (
    SELECT 
        ID,
        ROW_NUMBER() OVER (PARTITION BY CourseID ORDER BY ID ASC) AS RowNum
    FROM SignUp
) rn ON su.ID = rn.ID
WHERE su.SeqNo = 0 OR su.SeqNo IS NULL;

-- 顯示更新結果
SELECT '序號更新完成' AS [操作結果];
SELECT CourseID, COUNT(*) AS [人數], MIN(SeqNo) AS [最小序號], MAX(SeqNo) AS [最大序號]
FROM SignUp
WHERE SeqNo > 0
GROUP BY CourseID
ORDER BY CourseID;

COMMIT TRANSACTION;

-- =====================================================
-- 驗證結果
-- =====================================================

-- 查看更新後的資料
SELECT 
    ID,
    CourseID,
    SeqNo,
    Name,
    Mobile,
    CheckInTime,
    CheckOutTime
FROM SignUp
ORDER BY CourseID ASC, SeqNo ASC;

-- 檢查是否有未設定序號的記錄
SELECT 
    ID,
    CourseID,
    Name,
    Mobile
FROM SignUp
WHERE SeqNo = 0 OR SeqNo IS NULL
ORDER BY CourseID, ID;

-- 檢查序號是否重複
SELECT 
    CourseID,
    SeqNo,
    COUNT(*) AS [重複次數]
FROM SignUp
WHERE SeqNo > 0
GROUP BY CourseID, SeqNo
HAVING COUNT(*) > 1
ORDER BY CourseID, SeqNo;