Oracle面试题及答案整理
Oracle面试题及答案整理
1、表：table1(FId,Fclass,Fscore)，用最高效最简单的SQL列出各班成绩最高的列表，显示班级，成绩两个字段。
select fclass,max(fscore) from table1 group by fclass,fid
2、有一个表table1有两个字段FID，Fno，字都非空，写一个SQL语句列出该表中一个FID对应多个不同的Fno的纪录。
类如：
101a1001
101a1001
102a1002
102a1003
103a1004
104a1005
104a1006
105a1007
105a1007
105a1007
结果：
102a1002
102a1003
104a1005
104a1006
select t2.* from table1 t1, table1 t2 where t1.fid = t2.fid and t1.fno <> t2.fno;
3、有员工表empinfo
(
Fempno varchar2(10) not null pk,
Fempname varchar2(20) not null,
Fage number not null,
Fsalary number not null
);
假如数据量很大约1000万条；写一个你认为最高效的SQL，用一个SQL计算以下四种人：
fsalary>9999 and fage > 35
fsalary>9999 and fage < 35
fsalary <9999 and fage > 35
fsalary <9999 and fage < 35
每种员工的数量；
select sum(case when fsalary > 9999 and fage > 35 then 1
else 0end) as "fsalary>9999_fage>35",
sql查询面试题sum(case when fsalary > 9999 and fage < 35
then 1
else 0
end) as "fsalary>9999_fage<35",
sum(case when fsalary < 9999 and fage > 35
then 1
else 0
end) as "fsalary<9999_fage>35",
sum(case when fsalary < 9999 and fage < 35
then 1
else 0
end) as "fsalary<9999_fage<35"
from empinfo;
4、表A字段如下
month person income
月份人员收入
要求用一个SQL语句（注意是一个）的处所有人（不区分人员）每个月及上月和下月的总收入
要求列表输出为
月份当月收入上月收入下月收入
MONTHS PERSON INCOME
---------- ---------- ---------- 07 mantisXF 5000 06
mantisXF2 3500 06 mantisXF3 3000 05 mantisXF1
05 mantisXF6 2 00804 mantisXF7 1800 03 8mantisXF 4000 02 9mantisXF 4 00802 10mantisXF 3300 01
11mantisXF 4600 09 11mantisXF 6800
11 rows selected
select months, max(incomes), max(prev_months), max(next_months)
from (select months,
incomes,
decode(lag(months) over(order by months),
to_char(add_months(to_date(months, 'yyyymm'), -1), 'yyyymm'), lag(incomes) over(order by months), 0) as prev_months, decode(lead(months) over(order by months), to_char(add_months(to_date(months,
'yyyymm'), 1), 'yyyymm'), lead(incomes) over(order by months), 0) as next_months from (select months, sum(income) as incomes from a group by months) aa) aaagroup by months;
MONTHS MAX(INCOMES) MAX(PREV_MONTHS)
MAX(NEXT_MONTHS)---------- ------------ ---------------- ---------------- 01 4600 0 7500 02 7500 4600 4000