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现有a,b二表,它们的数据如下

a                                                                b

id    name                                                   id        stock

1       a                                                    1          15

2       b                                                    2          50

3       c    

Question1:

Select    * from   a inner join b on a.id=b.id

上述SQL语句返回的结果是?

Question2:

Select a.*,b.* from a left join b on a.id=b.id

上述SQL语句返回的结果是?

Question 3

Select a.*,b.* from a right join b on a.id=b.id

上述SQL语句返回的结果是?

现有MyTable:

日期         日产

1            3.333

2            4.222

3            1.555

4            9.888

Question 4

要求用SQL语句生成如下查询

日期         日产                      累计日产

1            3.333                     3.333

2            4.222                     7.555

3            1.555                     9.110

4            9.888                     18.998