行转列

Posted 2021-02-14 xiaohu666

列转行：利用max(case when then),不转行的列作为group by 的条件

SELECT
    `name`,
    MAX(
        CASE 
        WHEN  course=‘语文‘ THEN
            score
        END
    ) AS 语文,
    MAX(
        CASE 
        WHEN course=‘数学‘ THEN
            score
        END
    ) AS 数学, 
    MAX(
        CASE 
        WHEN course=‘英语‘ THEN
            score
        END
    ) AS 英语
FROM
    student
GROUP BY `name`
;

 

合并字段显示:利用group_cancat(course,”:”,”score”)

 

 不过行转列用decode()也行   DECODE与MAX的联合使用

SELECT DISTINCT EMP_NO,MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘01‘,CARD_FREQUENCY)) D01,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘02‘,CARD_FREQUENCY)) D02,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘03‘,CARD_FREQUENCY)) D03,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘04‘,CARD_FREQUENCY)) D04,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘05‘,CARD_FREQUENCY)) D05,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘06‘,CARD_FREQUENCY)) D06,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘07‘,CARD_FREQUENCY)) D07,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘08‘,CARD_FREQUENCY)) D08,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘09‘,CARD_FREQUENCY)) D09,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘10‘,CARD_FREQUENCY)) D10,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘11‘,CARD_FREQUENCY)) D11,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘12‘,CARD_FREQUENCY)) D12,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘13‘,CARD_FREQUENCY)) D13,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘14‘,CARD_FREQUENCY)) D14, 
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘15‘,CARD_FREQUENCY)) D15,
MAX(DECODE(TO_CHAR(WORK_DATE,‘DD‘),‘16‘,CARD_FREQUENCY)) D16
FROM HRA_READ_CARD_MONTH 
WHERE EMP_NO=‘090641‘ AND TO_CHAR(WORK_DATE,‘YYYY/MM‘)=‘2009/03‘
GROUP BY EMP_NO