Oracle行列互换总结

0    149    1

Tags:

👉 本文共约39653个字,系统预计阅读时间或需150分钟。

最近论坛很多人提的问题都与行列转换有关系,所以我对行列转换的相关知识做了一个总结,希望对大家有所帮助,同时有何错疏,恳请大家指出,我也是在写作过程中学习,算是一起和大家学习吧!

行列转换包括以下六种情况:

  1. 列转行
  2. 行转列
  3. 多列转换成字符串
  4. 多行转换成字符串
  5. 字符串转换成多列
  6. 字符串转换成多行

下面分别进行举例介绍。

首先声明一点,有些例子需要如下10g 及以后才有的知识:

A. 掌握model子句

B. 正则表达式

C. 加强的层次查询

讨论的适用范围只包括8i,9i,10g 及以后版本。

  1. 列转行

首先需要明白什么是列转行,简单的说就是将原表中的列名作为转换后的表的内容,这就是列转行。

CREATE TABLE t_col_row(

ID INT,

c1 VARCHAR2(10),

c2 VARCHAR2(10),

c3 VARCHAR2(10));

INSERT INTO t_col_row VALUES (1, 'v11', 'v21', 'v31');

INSERT INTO t_col_row VALUES (2, 'v12', 'v22', NULL);

INSERT INTO t_col_row VALUES (3, 'v13', NULL, 'v33');

INSERT INTO t_col_row VALUES (4, NULL, 'v24', 'v34');

INSERT INTO t_col_row VALUES (5, 'v15', NULL, NULL);

INSERT INTO t_col_row VALUES (6, NULL, NULL, 'v35');

INSERT INTO t_col_row VALUES (7, NULL, NULL, NULL);

COMMIT;

SELECT *** FROM t_col_row;**

Oracle行列互换总结

  1. UNION ALL ---主要方法

适用范围:8i,9i,10g 及以后版本

  1. 例一

SELECT id, 'c1' cn, c1 cv

FROM t_col_row

UNION ALL

SELECT id, 'c2' cn, c2 cv

FROM t_col_row

UNION ALL

SELECT id, 'c3' cn, c3 cv

FROM t_col_row;

Oracle行列互换总结

若空行不需要转换,只需加一个where条件,

WHERE COLUMN IS NOT NULL 即可。

如:

SELECT id, 'c1' cn, c1 cv

FROM t_col_row

where c1 is not null

UNION ALL

SELECT id, 'c2' cn, c2 cv

FROM t_col_row

where c2 is not null

UNION ALL

SELECT id, 'c3' cn, c3 cv

FROM t_col_row

where c3 is not null;

Oracle行列互换总结

  1. 例二

create table TEST_LHR

(

NAME VARCHAR2(255),

JANUARY NUMBER(18),

FEBRUARY NUMBER(18),

MARCH NUMBER(18),

APRIL NUMBER(18),

MAY NUMBER(18)

)

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('长寿', 58, 12, 26, 18, 269);

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('璧山', 33, 18, 17, 16, 206);

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('杨家坪', 72, 73, 79, 386, 327);

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('巫溪', 34, 9, 7, 21, 33);

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('丰都', 62, 46, 39, 36, 91);

insert into TEST_LHR (NAME, JANUARY, FEBRUARY, MARCH, APRIL, MAY)

values ('武隆', 136, 86, 44, 52, 142);

commit;

Oracle行列互换总结

SELECT *****

FROM (SELECT t.name,

'january' MONTH,

t.january v_num

FROM TEST_LHR t

UNION ALL

SELECT t.name,

'february' MONTH,

t.february v_num

FROM TEST_LHR t

UNION ALL

SELECT t.name,

'march' MONTH,

t.march v_num

FROM TEST_LHR t

UNION ALL

SELECT t.name,

'april' MONTH,

t.april v_num

FROM TEST_LHR t

UNION ALL

SELECT t.name,

'may' MONTH,

t.may v_num

FROM TEST_LHR t)

ORDER BY NAME;

Oracle行列互换总结

  1. insert all into ... select

首先创建需要的表,test_lhr1,

SQL> desc test_lhr1

Name Type Nullable Default Comments


NAME VARCHAR2(255) Y

MONTH VARCHAR2(8) Y

V_NUM NUMBER(18) Y

然后执行下边的sql语句:

insert all

into test_lhr1(NAME,month,v_num) values(name, 'may', may)

into test_lhr1(NAME,month,v_num) values(name, 'april', april)

into test_lhr1(NAME,month,v_num) values(name, 'february', february)

into test_lhr1(NAME,month,v_num) values(name, 'march', march)

into test_lhr1(NAME,month,v_num) values(name, 'january', january)

select t.name,t.january,t.february,t.march,t.april,t.may from test_lhr t;

commit;

别忘记commit操作,然后再查询test_lhr1,发现表中的数据就是列转成行了。

select *** from test_lhr1;**

Oracle行列互换总结

  1. MODEL

适用范围:10g 及以后

SELECT id,

cn,

cv

FROM t_col_row

MODEL RETURN

UPDATED ROWS PARTITION BY(ID)

DIMENSION BY(0 AS n)

MEASURES('xx' AS cn, 'yyy' AS cv, c1, c2, c3)

RULES UPSERT ALL(cn[1] = 'c1', cn[2] = 'c2', cn[3] = 'c3', cv[1] = c1[0], cv[2] = c2[0], cv[3] = c3[0])

ORDER BY ID,

cn;

Oracle行列互换总结

  1. COLLECTION

适用范围:8i,9i,10g 及以后版本

要创建一个对象和一个集合:

CREATE TYPE cv_pair AS OBJECT(cn VARCHAR2(10),cv VARCHAR2(10));

CREATE TYPE cv_varr AS VARRAY(8) OF cv_pair;

SELECT id,

t.cn AS cn,

t.cv AS cv

FROM t_col_row,

TABLE(cv_varr(cv_pair('c1', t_col_row.c1),

cv_pair('c2', t_col_row.c2),

cv_pair('c3', t_col_row.c3))) t

ORDER BY 1,

2;

Oracle行列互换总结

  1. 行转列

行转列就是将行数据内容作为列名。

CREATE TABLE t_row_col AS

SELECT id, 'c1' cn, c1 cv

FROM t_col_row

UNION ALL

SELECT id, 'c2' cn, c2 cv

FROM t_col_row

UNION ALL

SELECT id, 'c3' cn, c3 cv FROM t_col_row;

SELECT *** FROM t_row_col ORDER BY 1,2;**

Oracle行列互换总结

  1. AGGREGATE FUNCTION(max+decode) ---主要方法

用聚集函数来实现,适用范围:8i,9i,10g 及以后版本

  1. 例一

SELECT id,

MAX(decode(cn, 'c1', cv, NULL)) AS c1,

MAX(decode(cn, 'c2', cv, NULL)) AS c2,

MAX(decode(cn, 'c3', cv, NULL)) AS c3

FROM t_row_col

GROUP BY id

ORDER BY 1;

Oracle行列互换总结

? 注意:

  1. MAX聚集函数也可以用sum、min、avg 等其他聚集函数替代。
  2. 被指定的转置列只能有一列,但固定的列可以有多列,如果转置列有多列可以有2种办法解决,① 采用1.3.2创建临时表的方式

② 可以先转为单列,单列采用字符串的格式,然后将单列转换为多列

请看下面的例子:

SELECT mgr,

deptno,

empno,

ename

FROM emp

ORDER BY 1,

2;

Oracle行列互换总结

SELECT mgr,

deptno,

MAX(decode(empno, '7788', ename, NULL)) "7788",

MAX(decode(empno, '7902', ename, NULL)) "7902",

MAX(decode(empno, '7844', ename, NULL)) "7844",

MAX(decode(empno, '7521', ename, NULL)) "7521",

MAX(decode(empno, '7900', ename, NULL)) "7900",

MAX(decode(empno, '7499', ename, NULL)) "7499",

MAX(decode(empno, '7654', ename, NULL)) "7654"

FROM emp

WHERE mgr IN (7566, 7698)

AND deptno IN (20, 30)

GROUP BY mgr, deptno

ORDER BY 1, 2;

Oracle行列互换总结

这里转置列为empno,固定列为mgr,deptno。

1、固定列数的行列转换

student subject grade

---------------------------

student1 语文 80

student1 数学 70

student1 英语 60

student2 语文 90

student2 数学 80

student2 英语 100

……

转换为

语文 数学 英语

student1 80 70 60

student2 90 80 100

……

语句如下:

select student,sum(decode(subject,'语文', grade,null)) "语文",

sum(decode(subject,'数学', grade,null)) "数学",

sum(decode(subject,'英语', grade,null)) "英语"

from table

group by student

2、不定列行列转换

c1 c2

--------------

1 我

1 是

1 谁

2 知

2 道

3 不

……

转换为

1 我是谁

2 知道

3 不

这一类型的转换必须借助于PL/SQL来完成,这里给一个例子

CREATE OR REPLACE FUNCTION get_c2(tmp_c1 NUMBER)

RETURN VARCHAR2

IS

Col_c2 VARCHAR2(4000);

BEGIN

FOR cur IN (SELECT c2 FROM t WHERE c1=tmp_c1) LOOP

Col_c2 := Col_c2||cur.c2;

END LOOP;

Col_c2 := rtrim(Col_c2,1);

RETURN Col_c2;

END;

/

SQL> select distinct c1 ,get_c2(c1) cc2 from table;即可

还有一种行转列的方式,就是相同组中的行值变为单个列值,但转置的行值不变为列名:

ID CN_1 CV_1 CN_2 CV_2 CN_3 CV_3

1 c1 v11 c2 v21 c3 v31

2 c1 v12 c2 v22 c3

3 c1 v13 c2 c3 v33

4 c1 c2 v24 c3 v34

5 c1 v15 c2 c3

6 c1 c2 c3 v35

7 c1 c2 c3

这种情况可以用分析函数实现:

SELECT id,

MAX(decode(rn, 1, cn, NULL)) cn_1,

MAX(decode(rn, 1, cv, NULL)) cv_1,

MAX(decode(rn, 2, cn, NULL)) cn_2,

MAX(decode(rn, 2, cv, NULL)) cv_2,

MAX(decode(rn, 3, cn, NULL)) cn_3,

MAX(decode(rn, 3, cv, NULL)) cv_3

FROM (SELECT id,

cn,

cv,

row_number() over(PARTITION BY id ORDER BY cn, cv) rn

FROM t_row_col)

GROUP BY ID;

  1. 例二

SELECT t.name,

MAX(decode(t.month, 'may', t.v_num)) AS may,

MAX(decode(t.month, 'april', t.v_num)) AS april,

MAX(decode(t.month, 'february', t.v_num)) AS february,

MAX(decode(t.month, 'march', t.v_num)) AS march,

MAX(decode(t.month, 'january', t.v_num)) AS january

FROM test_lhr1 t

GROUP BY t.name;

Oracle行列互换总结

  1. 延伸

如果要实现对各个不同的区间进行统计,则:

SELECT *****

FROM test_lhr1 t

ORDER BY t.name,

t.month;

Oracle行列互换总结

SELECT t.name,

CASE

WHEN t.v_num < 100 THEN

本人提供Oracle(OCP、OCM)、MySQL(OCP)、PostgreSQL(PGCA、PGCE、PGCM)等数据库的培训和考证业务,私聊QQ646634621或微信db_bao,谢谢!
Oracle行列互换总结后续精彩内容已被小麦苗无情隐藏,请输入验证码解锁本站所有文章!
验证码:
请先关注本站微信公众号,然后回复“验证码”,获取验证码。在微信里搜索“DB宝”或者“www_xmmup_com”或者微信扫描右侧二维码都可以关注本站微信公众号。

标签:

Avatar photo

小麦苗

学习或考证,均可联系麦老师,请加微信db_bao或QQ646634621

您可能还喜欢...

发表回复

嘿,我是小麦,需要帮助随时找我哦。
  • 18509239930
  • 个人微信

  • DB宝
  • 个人邮箱
  • 点击加入QQ群
  • 个人微店

  • 回到顶部