mysql实现oracle分析函数功能 over
2016-08-10 23:50
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http://blog.csdn.net/mengtianyalll/article/details/45767603
部分内容来源：http://blog.csdn.net/jgmydsai/article/category/3139929
Mysql的if函数
格式：IF(Condition,A,B)意义：当Condition为TRUE时，返回A；当Condition为FALSE时，返回B。
作用：作为条件语句使用。
例子：
SELECT
fullName,
actualHour,
planhour,
annotatorId,
IF(actualHour-planhour>0.01,1,IF(actualHour-planhour<-0.01,-1,0)) ASratio
FROM
Table01
mysql查询结果添加序列号
第一种方法：select (@i:=@i+1) as i,table_name.* from table_name,(select @i:=0) as it
第二种方法：
set @rownum=0;
select @rownum:=@rownum+1 as rownum, t.username from auth_user t limit 1,5;
mysql之 sum() over(partition by)
[sql] view
plaincopy
1. SELECT empno,
2. ename,
3. sal,
4. IF(@deptno = deptno, @sal := @sal, @sal := s_sal) AS s_sal,
5. @deptno := deptno
6. FROM
7. (
8. SELECT empno,
9. ename,
10. sal,
11. IF(@deptno = deptno, @sal := @sal + sal, @sal := sal) AS s_sal,
12. @deptno := deptno AS deptno
13. FROM (SELECT @sal := 0, @deptno := 0) a0, emp t
14. ORDER BY deptno, empno
15. )e
16. ORDER BY deptno, empno DESC;
1. +-------+--------+------+-------+-------------------+
2. | empno | ename | sal | s_sal | @deptno := deptno |
3. +-------+--------+------+-------+-------------------+
4. | 7934 | MILLER | 1300 | 8750 | 10 |
5. | 7839 | KING | 5000 | 8750 | 10 |
6. | 7782 | CLARK | 2450 | 8750 | 10 |
7. | 7902 | FORD | 3000 | 10875 | 20 |
8. | 7876 | ADAMS | 1100 | 10875 | 20 |
9. | 7788 | SCOTT | 3000 | 10875 | 20 |
10. | 7566 | JONES | 2975 | 10875 | 20 |
11. | 7369 | SMITH | 800 | 10875 | 20 |
12. | 7900 | JAMES | 950 | 9400 | 30 |
13. | 7844 | TURNER | 1500 | 9400 | 30 |
14. | 7698 | BLAKE | 2850 | 9400 | 30 |
15. | 7654 | MARTIN | 1250 | 9400 | 30 |
16. | 7521 | WARD | 1250 | 9400 | 30 |
17. | 7499 | ALLEN | 1600 | 9400 | 30 |
18. +-------+--------+------+-------+-------------------+
19. 14 rows in set (0.01 sec)
max() over()
今天有人问max() over()的需求在mysql中怎么写。同以前讲过的几个例子一样，虽然mysql中没有分析函数，可max() over()的方法一样很容易实现
max() over()
[sql] view
plaincopy
1. mysql> set @max_sal=0;
2. Query OK, 0 rows affected (0.00 sec)
3.
4. mysql> select if(@max_sal=0,@max_sal:=sal,@max_sal) as max_sal,sal from emp order by sal desc;
5. +---------+------+
6. | max_sal | sal |
7. +---------+------+
8. | 5000 | 5000 |
9. | 5000 | 3000 |
10. | 5000 | 3000 |
11. | 5000 | 2975 |
12. | 5000 | 2850 |
13. | 5000 | 2450 |
14. | 5000 | 1600 |
15. | 5000 | 1500 |
16. | 5000 | 1300 |
17. | 5000 | 1250 |
18. | 5000 | 1250 |
19. | 5000 | 1100 |
20. | 5000 | 950 |
21. | 5000 | 800 |
22. +---------+------+
23. 14 rows in set (0.00 sec)
特殊的行转列需求
[sql] viewplaincopy
1. mysql> select * from ddd;
2. +------+------+------+------+
3. | stat | yi | er | san |
4. +------+------+------+------+
5. | a | 1 | 2 | 3 |
6. | a | 4 | 5 | 6 |
7. | b | 11 | 22 | 3 |
8. | b | 5 | 61 | 82 |
9. +------+------+------+------+
10. 4 rows in set (0.00 sec)
把上面的数据行转列，结果如下
[sql] view
plaincopy
1. +------+------+------+------+------+------+------+------+------+------+
2. | stat | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8 | c9 |
3. +------+------+------+------+------+------+------+------+------+------+
4. | a | 1 | 2 | 3 | 4 | 5 | 6 | NULL | NULL | NULL |
5. | b | 3 | 5 | 11 | 22 | 61 | 82 | NULL | NULL | NULL |
6. +------+------+------+------+------+------+------+------+------+------+
7. 2 rows in set (0.01 sec)
这种需求在oracle中比较容易实现，因为oracle中有row_number可以生成序号。mysql中就只有另找方法了
[sql] view
plaincopy
1. set @rn=0;
2. set @stat='';
3. select stat,
4. max(case when rn = 1 then yi end) as c1,
5. max(case when rn = 2 then yi end) as c2,
6. max(case when rn = 3 then yi end) as c3,
7. max(case when rn = 4 then yi end) as c4,
8. max(case when rn = 5 then yi end) as c5,
9. max(case when rn = 6 then yi end) as c6,
10. max(case when rn = 7 then yi end) as c7,
11. max(case when rn = 8 then yi end) as c8,
12. max(case when rn = 9 then yi end) as c9
13. from
14. (
15. SELECT stat,
16. yi,
17. IF(@stat = stat, @rn := @rn + 1, @rn := 1) AS rn,
18. @stat := stat AS last_stat
19. from
20. (
21. select stat,yi from ddd
22. union all
23. select stat,er from ddd
24. union all
25. select stat,san from ddd
26. ) as a
27. order by stat,yi
28. ) as a
29. group by stat;
通过分组生成的序号来定位，就可以把对应的值转到相应位置了
[sql] view
plaincopy
1. mysql> set @rn=0;
2. Query OK, 0 rows affected (0.00 sec)
3.
4. mysql> set @stat='';
5. Query OK, 0 rows affected (0.00 sec)
6.
7. mysql> select stat,
8. -> max(case when rn = 1 then yi end) as c1,
9. -> max(case when rn = 2 then yi end) as c2,
10. -> max(case when rn = 3 then yi end) as c3,
11. -> max(case when rn = 4 then yi end) as c4,
12. -> max(case when rn = 5 then yi end) as c5,
13. -> max(case when rn = 6 then yi end) as c6,
14. -> max(case when rn = 7 then yi end) as c7,
15. -> max(case when rn = 8 then yi end) as c8,
16. -> max(case when rn = 9 then yi end) as c9
17. -> from
18. -> (
19. -> SELECT stat,
20. -> yi,
21. -> IF(@stat = stat, @rn := @rn + 1, @rn := 1) AS rn,
22. -> @stat := stat AS last_stat
23. -> from
24. -> (
25. -> select stat,yi from ddd
26. -> union all
27. -> select stat,er from ddd
28. -> union all
29. -> select stat,san from ddd
30. -> ) as a
31. -> order by stat,yi
32. -> ) as a
33. -> group by stat;
34. +------+------+------+------+------+------+------+------+------+------+
35. | stat | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8 | c9 |
36. +------+------+------+------+------+------+------+------+------+------+
37. | a | 1 | 2 | 3 | 4 | 5 | 6 | NULL | NULL | NULL |
38. | b | 3 | 5 | 11 | 22 | 61 | 82 | NULL | NULL | NULL |
39. +------+------+------+------+------+------+------+------+------+------+
40. 2 rows in set (0.01 sec)
mysql之wm_concat
[sql] viewplaincopy
1. SET @enames='';
2. SET @last_deptno=-1;
3. SELECT deptno, MAX(enames) AS enames
4. FROM (SELECT deptno,
5. IF(@last_deptno = deptno, @rn := @rn + 1, @rn := 1) AS rn,
6. IF(@last_deptno = deptno,
7. @enames := concat(@enames, ',', ename),
8. @enames := ename) AS enames,
9. @last_deptno := deptno AS last_deptno
10. FROM emp
11. ORDER BY deptno, empno)a
12. GROUP BY deptno;
13.
14. +--------+--------------------------------------+
15. | deptno | enames |
16. +--------+--------------------------------------+
17. | 10 | CLARK,KING,MILLER |
18. | 20 | SMITH,JONES,SCOTT,ADAMS,FORD |
19. | 30 | ALLEN,WARD,MARTIN,BLAKE,TURNER,JAMES |
20. +--------+--------------------------------------+
21. 3 rows in set (0.01 sec)
mysql之累加
[sql] view
plaincopy
1. SET @add_sal=0;
2. SELECT deptno, empno, ename, sal, @add_sal := @add_sal + sal AS add_sal
3. FROM emp
4. ORDER BY empno;
5.
6. +--------+-------+--------+------+---------+
7. | deptno | empno | ename | sal | add_sal |
8. +--------+-------+--------+------+---------+
9. | 20 | 7369 | SMITH | 800 | 800 |
10. | 30 | 7499 | ALLEN | 1600 | 2400 |
11. | 30 | 7521 | WARD | 1250 | 3650 |
12. | 20 | 7566 | JONES | 2975 | 6625 |
13. | 30 | 7654 | MARTIN | 1250 | 7875 |
14. | 30 | 7698 | BLAKE | 2850 | 10725 |
15. | 10 | 7782 | CLARK | 2450 | 13175 |
16. | 20 | 7788 | SCOTT | 3000 | 16175 |
17. | 10 | 7839 | KING | 5000 | 21175 |
18. | 30 | 7844 | TURNER | 1500 | 22675 |
19. | 20 | 7876 | ADAMS | 1100 | 23775 |
20. | 30 | 7900 | JAMES | 950 | 24725 |
21. | 20 | 7902 | FORD | 3000 | 27725 |
22. | 10 | 7934 | MILLER | 1300 | 29025 |
23. +--------+-------+--------+------+---------+
24. 14 rows in set (0.01 sec)
[sql] view
plaincopy
1. SET @add_sal=0;
2. SET @last_deptno=-1;
3. SELECT deptno,
4. empno,
5. ename,
6. sal,
7. IF(@last_deptno = deptno, @rn := @rn + 1, @rn := 1) AS rn,
8. IF(@last_deptno = deptno, @add_sal := @add_sal + sal, @add_sal := sal) AS add_sal,
9. @last_deptno := deptno AS last_deptno
10. FROM emp
11. ORDER BY deptno, sal;
12.
13. +--------+-------+--------+------+------+---------+-------------+
14. | deptno | empno | ename | sal | rn | add_sal | last_deptno |
15. +--------+-------+--------+------+------+---------+-------------+
16. | 10 | 7934 | MILLER | 1300 | 1 | 1300 | 10 |
17. | 10 | 7782 | CLARK | 2450 | 2 | 3750 | 10 |
18. | 10 | 7839 | KING | 5000 | 3 | 8750 | 10 |
19. | 20 | 7369 | SMITH | 800 | 1 | 800 | 20 |
20. | 20 | 7876 | ADAMS | 1100 | 2 | 1900 | 20 |
21. | 20 | 7566 | JONES | 2975 | 3 | 4875 | 20 |
22. | 20 | 7788 | SCOTT | 3000 | 4 | 7875 | 20 |
23. | 20 | 7902 | FORD | 3000 | 5 | 10875 | 20 |
24. | 30 | 7900 | JAMES | 950 | 1 | 950 | 30 |
25. | 30 | 7654 | MARTIN | 1250 | 2 | 2200 | 30 |
26. | 30 | 7521 | WARD | 1250 | 3 | 3450 | 30 |
27. | 30 | 7844 | TURNER | 1500 | 4 | 4950 | 30 |
28. | 30 | 7499 | ALLEN | 1600 | 5 | 6550 | 30 |
29. | 30 | 7698 | BLAKE | 2850 | 6 | 9400 | 30 |
30. +--------+-------+--------+------+------+---------+-------------+
31. 14 rows in set (0.05 sec)
mysql 之 rank()
over()
1. SET @rn=0; 2. SET @dense_rank=0;
3. SET @last_deptno=-1;
4. SET @last_sal=-1;
5. SET @ADD = 0;
6. SELECT deptno,
7. empno,
8. ename,
9. sal,
10. IF(@last_deptno = deptno, @rn := @rn + 1, @rn := 1) AS rn,
11. IF(@last_sal = sal,@dense_rank := @dense_rank,@dense_rank := @rn) AS rank,
12. IF(@last_deptno = deptno, @last_sal := sal, @last_sal := -1) AS last_sal,
13. @last_deptno := deptno AS last_deptno
14. FROM EMP
15. ORDER BY deptno, sal;
16.
17. +--------+-------+--------+------+------+------------+----------+-------------+
18. | deptno | empno | ename | sal | rn | dense_rank | last_sal | last_deptno |
19. +--------+-------+--------+------+------+------------+----------+-------------+
20. | 10 | 7934 | MILLER | 1300 | 1 | 1 | -1 | 10 |
21. | 10 | 7782 | CLARK | 2450 | 2 | 2 | 2450 | 10 |
22. | 10 | 7839 | KING | 5000 | 3 | 3 | 5000 | 10 |
23. | 20 | 7369 | SMITH | 800 | 1 | 1 | -1 | 20 |
24. | 20 | 7876 | ADAMS | 1100 | 2 | 2 | 1100 | 20 |
25. | 20 | 7566 | JONES | 2975 | 3 | 3 | 2975 | 20 |
26. | 20 | 7788 | SCOTT | 3000 | 4 | 4 | 3000 | 20 |
27. | 20 | 7902 | FORD | 3000 | 5 | 4 | 3000 | 20 |
28. | 30 | 7900 | JAMES | 950 | 1 | 1 | -1 | 30 |
29. | 30 | 7654 | MARTIN | 1250 | 2 | 2 | 1250 | 30 |
30. | 30 | 7521 | WARD | 1250 | 3 | 2 | 1250 | 30 |
31. | 30 | 7844 | TURNER | 1500 | 4 | 4 | 1500 | 30 |
32. | 30 | 7499 | ALLEN | 1600 | 5 | 5 | 1600 | 30 |
33. | 30 | 7698 | BLAKE | 2850 | 6 | 6 | 2850 | 30 |
34. +--------+-------+--------+------+------+------------+----------+-------------+
35. 14 rows in set (0.00 sec)
mysq 之 dense_rank()
over()
1. SET @rn=0; 2. SET @last_deptno=-1;
3. SET @last_sal=-1;
4. SELECT deptno,
5. empno,
6. ename,
7. sal,
8. IF(@last_deptno = deptno, @rn := @rn + IF(@last_sal = sal,0,1), @rn := 1) AS dense_rank,
9. IF(@last_deptno = deptno, @last_sal := sal, @last_sal := -1) AS last_sal,
10. @last_deptno := deptno AS last_deptno
11. FROM EMP
12. ORDER BY deptno, sal;
13.
14. +--------+-------+--------+------+------------+----------+-------------+
15. | deptno | empno | ename | sal | dense_rank | last_sal | last_deptno |
16. +--------+-------+--------+------+------------+----------+-------------+
17. | 10 | 7934 | MILLER | 1300 | 1 | -1 | 10 |
18. | 10 | 7782 | CLARK | 2450 | 2 | 2450 | 10 |
19. | 10 | 7839 | KING | 5000 | 3 | 5000 | 10 |
20.
21. | 20 | 7369 | SMITH | 800 | 1 | -1 | 20 |
22. | 20 | 7876 | ADAMS | 1100 | 2 | 1100 | 20 |
23. | 20 | 7566 | JONES | 2975 | 3 | 2975 | 20 |
24. | 20 | 7788 | SCOTT | 3000 | 4 | 3000 | 20 |
25. | 20 | 7902 | FORD | 3000 | 4 | 3000 | 20 |
26.
27. | 30 | 7900 | JAMES | 950 | 1 | -1 | 30 |
28. | 30 | 7654 | MARTIN | 1250 | 2 | 1250 | 30 |
29. | 30 | 7521 | WARD | 1250 | 2 | 1250 | 30 |
30. | 30 | 7844 | TURNER | 1500 | 3 | 1500 | 30 |
31. | 30 | 7499 | ALLEN | 1600 | 4 | 1600 | 30 |
32. | 30 | 7698 | BLAKE | 2850 | 5 | 2850 | 30 |
33. +--------+-------+--------+------+------------+----------+-------------+
34. 14 rows in set (0.00 sec)
mysql 之 row_number()
over ()
1. SET @rn=0; 2. SET @last_deptno=0;
3. SELECT deptno,
4. empno,
5. ename,
6. sal,
7. IF(@last_deptno = deptno, @rn := @rn + 1, @rn := 1) AS rn,
8. @last_deptno := deptno AS last_deptno
9. FROM EMP
10. ORDER BY deptno, sal;
11.
12. +--------+-------+--------+------+------+-------------+
13. | deptno | empno | ename | sal | rn | last_deptno |
14. +--------+-------+--------+------+------+-------------+
15. | 10 | 7934 | MILLER | 1300 | 1 | 10 |
16. | 10 | 7782 | CLARK | 2450 | 2 | 10 |
17. | 10 | 7839 | KING | 5000 | 3 | 10 |
18.
19. | 20 | 7369 | SMITH | 800 | 1 | 20 |
20. | 20 | 7876 | ADAMS | 1100 | 2 | 20 |
21. | 20 | 7566 | JONES | 2975 | 3 | 20 |
22. | 20 | 7788 | SCOTT | 3000 | 4 | 20 |
23. | 20 | 7902 | FORD | 3000 | 5 | 20 |
24.
25. | 30 | 7900 | JAMES | 950 | 1 | 30 |
26. | 30 | 7654 | MARTIN | 1250 | 2 | 30 |
27. | 30 | 7521 | WARD | 1250 | 3 | 30 |
28. | 30 | 7844 | TURNER | 1500 | 4 | 30 |
29. | 30 | 7499 | ALLEN | 1600 | 5 | 30 |
30. | 30 | 7698 | BLAKE | 2850 | 6 | 30 |
31. +--------+-------+--------+------+------+-------------+
32. 14 rows in set (0.01 sec)
mysql 生成 rownum
1. SET @rn=0;
2. SELECT deptno,
3. empno,
4. ename,
5. @rn := @rn + 1 AS rn
6. FROM EMP
7. ORDER BY 1, 2;
8.
9. mysql> SET @rn=0;
10. Query OK, 0 rows affected (0.00 sec)
11.
12. mysql> SELECT deptno,
13. -> empno,
14. -> ename,
15. -> @rn := @rn + 1 AS rn
16. -> FROM EMP
17. -> ORDER BY 1, 2;
18. +--------+-------+--------+------+
19. | deptno | empno | ename | rn |
20. +--------+-------+--------+------+
21. | 10 | 7782 | CLARK | 1 |
22. | 10 | 7839 | KING | 2 |
23. | 10 | 7934 | MILLER | 3 |
24. | 20 | 7369 | SMITH | 4 |
25. | 20 | 7566 | JONES | 5 |
26. | 20 | 7788 | SCOTT | 6 |
27. | 20 | 7876 | ADAMS | 7 |
28. | 20 | 7902 | FORD | 8 |
29. | 30 | 7499 | ALLEN | 9 |
30. | 30 | 7521 | WARD | 10 |
31. | 30 | 7654 | MARTIN | 11 |
32. | 30 | 7698 | BLAKE | 12 |
33. | 30 | 7844 | TURNER | 13 |
34. | 30 | 7900 | JAMES | 14 |
35. +--------+-------+--------+------+
36. 14 rows in set (0.00 sec)
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