Oracle 行轉列總結 Case When,Decode,PIVOT 三種方式

Decode 方式

SELECT a.COUNTRY AS "國家",
SUM(DECODE(a.SEX, 1, a.POPULCATION)) AS "男",
SUM(DECODE(a.SEX, 2, a.POPULCATION)) AS "女"
FROM populations a
GROUP BY a.COUNTRY

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Case When 方式

SELECT a.COUNTRY AS "國家",
SUM(CASE
WHEN a.SEX = 1 THEN
a.POPULCATION
END) AS "男",
SUM(CASE
WHEN a.SEX = 2 THEN
a.POPULCATION
END) AS "女"
FROM populations a
GROUP BY a.COUNTRY

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PIVOT 方式 11G特有的方式

SELECT *
FROM (SELECT a.COUNTRY AS "國家", a.SEX, a.POPULCATION FROM populations a)
PIVOT(
SUM(POPULCATION)
FOR SEX IN(1 AS "男",2 AS "女"))