Sql 逐行(无光标或循环)
这里我有一些学生的卷号和课程代码的样本数据Sql 逐行(无光标或循环),sql,tsql,sql-server-2012,Sql,Tsql,Sql Server 2012,这里我有一些学生的卷号和课程代码的样本数据 ------------------------- Roll CourseCode -------------------------- 1011 CS201 2213 CS201 3312 CS101 4000 CS201 1011 CS101 5312 ME102 1011 PT101
-------------------------
Roll CourseCode
--------------------------
1011 CS201
2213 CS201
3312 CS101
4000 CS201
1011 CS101
5312 ME102
1011 PT101
3312 ME102
结果应为Coursecode
及其考试日期
e、 g(分类不同的课程代码)
首先,我选择CS201并指定课程代码日期;将它放在一个临时表中,然后我选择了CS101,并将在临时表中检查此Coursecode的RollNumber是否与临时表中其他Coursecode的任何其他RollNumber匹配
---------------------
Code Date
---------------------
CS101 1
CS201 2
ME102 1
PT101 3
我的代码:
包含所有数据(课程代码、卷号)#temp3
(输出数据)#mytemp1
SET @cursor = CURSOR FOR
SELECT DISTINCT coursecode
FROM #temp3
ORDER BY CourseCode
OPEN @cursor
FETCH NEXT
FROM @cursor INTO @cursorid
WHILE @@FETCH_STATUS = 0
BEGIN
BEGIN
SET @j=1
WHILE(@j !=9999999)
BEGIN
IF( SELECT COUNT(*) FROM #temp3 WHERE CourseCode = @cursorid AND RegdNo IN (
SELECT RegdNo FROM #temp3 WHERE CourseCode IN ( SELECT coursecode FROM #myTemp1 WHERE counter1 = @j)
)) = 0
BEGIN
INSERT INTO #myTemp1 VALUES (@cursorid,@j)
SET @j=9999999
END
ELSE
BEGIN
SET @j = @j + 1
END
END
END
FETCH NEXT
FROM @cursor INTO @cursorid
END
CLOSE @cursor
DEALLOCATE @cursor
此代码工作正常,但占用的时间太长(4110222条记录)
任何帮助都将不胜感激以下是一些代码。我相信您的输出有错误,
CS101
应该在CS201
之前:
DECLARE @t TABLE ( Roll INT, Code CHAR(5) )
INSERT INTO @t
VALUES ( 1011, 'CS201' ),
( 2213, 'CS201' ),
( 3312, 'CS101' ),
( 4000, 'CS201' ),
( 1011, 'CS101' ),
( 5312, 'ME102' ),
( 1011, 'PT101' ),
( 3319, 'ME102' );
WITH cte1
AS ( SELECT code ,
ROW_NUMBER() OVER ( ORDER BY Code ) AS rn
FROM @t
GROUP BY code
),
cte2
AS ( SELECT code ,
rn ,
1 AS Date
FROM cte1
WHERE rn = 1
UNION ALL
SELECT c1.code ,
c1.rn ,
CASE WHEN EXISTS ( SELECT *
FROM @t a
JOIN @t b ON a.Roll = b.Roll
JOIN cte1 c ON c.rn < c1.rn
AND b.Code = c.code
WHERE a.code = c1.code ) THEN 1
ELSE 0
END
FROM cte1 c1
JOIN cte2 c2 ON c1.rn = c2.rn + 1
),
cte3
AS ( SELECT Code ,
CASE WHEN Date = 0 THEN 1
ELSE SUM(Date) OVER ( ORDER BY rn )
END AS Date
FROM cte2
)
SELECT * FROM cte3
编辑:
cte1
将返回:
code rn
CS101 1
CS201 2
ME102 3
PT101 4
主要工作在cte2
中完成。它是递归的公共表表达式。
首先,从cte1
中获取顶部1行:
SELECT code ,
rn ,
1 AS Date
FROM cte1
WHERE rn = 1
然后递归进行:
您将在cte2
上加入cte1
,并选择以下RN(2,3…)并检查CS201
中是否有与先前代码中的卷匹配的卷(CS101
),在第一步中,检查ME102
中是否有与先前代码中的卷匹配的卷(CS101,CS201
)在第二步等中,如果存在,则返回1,否则返回0:
code rn Date
CS101 1 1
CS201 2 1
ME102 3 0
PT101 4 1
最后一个cte3
执行以下操作:如果日期=0,则返回1,否则返回前几行(包括当前行)中的日期总和
EDIT1:
由于我的理解不正确,这里还有一句话:
WITH cte
AS ( SELECT code ,
ROW_NUMBER() OVER ( ORDER BY Code ) AS rn
FROM @t
GROUP BY code
)
SELECT co.Code,
DENSE_RANK() OVER(ORDER BY ISNULL(o.Code, co.Code)) AS Date
FROM cte co
OUTER APPLY(SELECT TOP 1 ci.Code
FROM cte ci
WHERE ci.rn < co.rn AND
NOT EXISTS(SELECT * FROM @t
WHERE code = ci.code AND
roll IN(SELECT roll FROM @t WHERE code = co.code)) ORDER BY ci.rn) o
ORDER BY co.rn
EDIT2:
这太疯狂了,但下面的代码似乎很有效:
WITH cte
AS ( SELECT * ,
ROW_NUMBER() OVER ( PARTITION BY roll ORDER BY Code ) AS Date
FROM @t
)
SELECT Code ,
MAX(Date) AS Date
FROM cte
GROUP BY Code
我们可以使用CTE有效地完成这项工作。我会给你举个例子让我们看看。
Code Date
CS101 1
CS201 2
ME102 1
PT101 2
WITH cte
AS ( SELECT * ,
ROW_NUMBER() OVER ( PARTITION BY roll ORDER BY Code ) AS Date
FROM @t
)
SELECT Code ,
MAX(Date) AS Date
FROM cte
GROUP BY Code