Question

我有两个表，每个表都将自己的结果集生成为一行。我想将这些结果集合成一行。例如：

SELECT *
FROM Table 1
WHERE Year = 2012 AND Quarter = 1

结果：

Year  Quarter  Name  State  Mail
2012  1        Bob   NY     bob@gmail

查询＃2：

SELECT *
FROM Table 2
WHERE Year = 2012 AND Quarter = 1

结果：

Year  Quarter  Name  State  Mail
2012  1        Greg  DC     greg@gmail

期望的结果集：

SELECT *
FROM Table 3
WHERE Year = 2012 AND Quarter = 1

Year  Quarter  T1Name  T1State  T1Mail     T2Name  T2State  T2Mail
2012  1        Bob     NY       bob@gmail  Greg    DC       greg@gmail

将结果连接/旋转到Year和Quarter的组合，这些组合将通过参数提供给查询。任何帮助将不胜感激。提前谢谢！

Answer 1

除非我遗漏了某些内容，否则您似乎可以加入year / quarter上的表格，似乎无需转动数据：

select t1.year, 
  t1.quarter,
  t1.name t1Name,
  t1.state t1State,
  t1.mail t1Mail,
  t2.name t2Name,
  t2.state t2State,
  t2.mail t2Mail
from table1 t1
inner join table2 t2
  on t1.year = t2.year
  and t1.quarter = t2.quarter
where t1.year = 2012
  and t1.quarter = 1;

请参阅SQL Fiddle with Demo

现在，如果对两个表中是否存在year和quarter存在疑问，那么您可以使用FULL OUTER JOIN：

select coalesce(t1.year, t2.year) year, 
  coalesce(t1.quarter, t2.quarter) quarter,
  t1.name t1Name,
  t1.state t1State,
  t1.mail t1Mail,
  t2.name t2Name,
  t2.state t2State,
  t2.mail t2Mail
from table1 t1
full outer join table2 t2
  on t1.year = t2.year
  and t1.quarter = t2.quarter
where (t1.year = 2012 and t1.quarter = 2)
  or  (t2.year = 2012 and t2.quarter = 2)

请参阅SQL Fiddle with Demo

Answer 2

您需要做的就是确定连接条件，即两个表中必须具有匹配值的列。在你的情况下，它看起来是年和季所以你会写一些类似select * from Table_1 A Join Table_2 B ON A.year = B.year and A.quarter = B.quarter

Answer 3

如果您有两个返回一行的查询，则可以使用cross join将它们放在一个结果行中：

select t1.Year, t1.Quarter, T1.Name, T1.State, T1.Mail, T2.Name, T2.State, T2.Mail
from (SELECT *
      FROM Table 1
      WHERE Year = 2012 AND Quarter = 1
     ) t1 cross join
     (SELECT *
      FROM Table 2
      WHERE Year = 2012 AND Quarter = 1
     ) t2

如果您希望它们位于不同的行中，则使用union all（假设它们在相同位置具有相同的列）。

T-SQL：水平连接结果集

3 个答案: