MySQLの行と列をオンにするカラムスイッチ
ライン転送コラム
例：図1図に変換される2の結果を示します。
図1
図2
|
1
2
3
4
5
6
7
|
CREATE
TABLE
`TEST_TB_GRADE` (
`ID`
int
(10)
NOT
NULL
AUTO_INCREMENT,
`USER_NAME`
varchar
(20)
DEFAULT
NULL
,
`COURSE`
varchar
(20)
DEFAULT
NULL
,
`SCORE`
float
DEFAULT
'0'
,
PRIMARY
KEY
(`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1
DEFAULT
CHARSET=utf8;
|
|
1
2
3
4
5
6
7
8
9
10
|
insert
into
TEST_TB_GRADE(USER_NAME, COURSE, SCORE)
values
(
"张三"
,
"数学"
, 34),
(
"张三"
,
"语文"
, 58),
(
"张三"
,
"英语"
, 58),
(
"李四"
,
"数学"
, 45),
(
"李四"
,
"语文"
, 87),
(
"李四"
,
"英语"
, 45),
(
"王五"
,
"数学"
, 76),
(
"王五"
,
"语文"
, 34),
(
"王五"
,
"英语"
, 89);
|
ライン転送列のSQL：
|
1
2
3
4
5
6
|
SELECT
user_name ,
MAX
(
CASE
course
WHEN
'数学'
THEN
score
ELSE
0
END
) 数学,
MAX
(
CASE
course
WHEN
'语文'
THEN
score
ELSE
0
END
) 语文,
MAX
(
CASE
course
WHEN
'英语'
THEN
score
ELSE
0
END
) 英语
FROM
test_tb_grade
GROUP
BY
USER_NAME;
|
コラムスイッチ
たとえば、次の図に変換する1図3に結果を示します。
図3
SQLのカラムスイッチ：
|
1
2
3
4
|
select
user_name,
'语文'
COURSE , CN_SCORE
as
SCORE
from
test_tb_grade2
union
select
user_name,
'数学'
COURSE, MATH_SCORE
as
SCORE
from
test_tb_grade2
union
select
user_name,
'英语'
COURSE, EN_SCORE
as
SCORE
from
test_tb_grade2
order
by
user_name,COURSE;
|
ライン転送コラム
例：図1図に変換される2の結果を示します。
図1
図2
|
1
2
3
4
5
6
7
|
CREATE
TABLE
`TEST_TB_GRADE` (
`ID`
int
(10)
NOT
NULL
AUTO_INCREMENT,
`USER_NAME`
varchar
(20)
DEFAULT
NULL
,
`COURSE`
varchar
(20)
DEFAULT
NULL
,
`SCORE`
float
DEFAULT
'0'
,
PRIMARY
KEY
(`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=1
DEFAULT
CHARSET=utf8;
|
|
1
2
3
4
5
6
7
8
9
10
|
insert
into
TEST_TB_GRADE(USER_NAME, COURSE, SCORE)
values
(
"张三"
,
"数学"
, 34),
(
"张三"
,
"语文"
, 58),
(
"张三"
,
"英语"
, 58),
(
"李四"
,
"数学"
, 45),
(
"李四"
,
"语文"
, 87),
(
"李四"
,
"英语"
, 45),
(
"王五"
,
"数学"
, 76),
(
"王五"
,
"语文"
, 34),
(
"王五"
,
"英语"
, 89);
|
ライン転送列のSQL：
|
1
2
3
4
5
6
|
SELECT
user_name ,
MAX
(
CASE
course
WHEN
'数学'
THEN
score
ELSE
0
END
) 数学,
MAX
(
CASE
course
WHEN
'语文'
THEN
score
ELSE
0
END
) 语文,
MAX
(
CASE
course
WHEN
'英语'
THEN
score
ELSE
0
END
) 英语
FROM
test_tb_grade
GROUP
BY
USER_NAME;
|
コラムスイッチ
たとえば、次の図に変換する1図3に結果を示します。
図3
SQLのカラムスイッチ：
|
1
2
3
4
|
select
user_name,
'语文'
COURSE , CN_SCORE
as
SCORE
from
test_tb_grade2
union
select
user_name,
'数学'
COURSE, MATH_SCORE
as
SCORE
from
test_tb_grade2
union
select
user_name,
'英语'
COURSE, EN_SCORE
as
SCORE
from
test_tb_grade2
order
by
user_name,COURSE;
|