面試遇到的一些SQL語句題目
阿新 • • 發佈:2018-11-23
最近忙著找工作,也面試了不少公司,做了不少筆試題目,現在把遇到的一些SQL 題目貼出來:
1.把以下表
year month amount
1991 1 1.1
1991 2 1.2
1991 3 1.3
1991 4 1.4
1992 1 2.1
1992 2 2.2
1992 3 2.3
1992 4 2.4
查成這樣一個結果
year m1 m2 m3 m4
1991 1.1 1.2 1.3 1.4
1992 2.1 2.2 2.3 2.4
SELECT YEAR, ( SELECT amount FROM yearr yearr2 WHERE MONTH = 1 AND yearr. YEAR = yearr2. YEAR ) AS m1, ( SELECT amount FROM yearr yearr2 WHERE MONTH = 2 AND yearr. YEAR = yearr2. YEAR ) AS m2, ( SELECT amount FROM yearr yearr2 WHERE MONTH = 3 AND yearr. YEAR = yearr2. YEAR ) AS m3, ( SELECT amount FROM yearr yearr2 WHERE MONTH = 4 AND yearr. YEAR = yearr2. YEAR ) AS m4 FROM yearr GROUP BY YEAR;