按城市

Question

我对sql很陌生，这似乎超出了我的技能。

我需要从2个连接表中创建以下列表：

City   | TotalResult | Result= A or B | Result= C or D or E | Result = F 
city1  |      10     |        3       |          5          |      2     
city2  |      3      |        2       |          0          |      1     

表结构是：

Tbl1: id (primary), city, result
Tbl2: code (primary), moment, status
Joining of the tables is easy:
select * from Tbl1 t1 join Tbl2 t2 on t1.id=t2.code

我首先尝试嵌套选择，但我不能或不知道如何匹配2个条件，城市+“结果= A或B”，除非我指定特定城市，在这种情况下无法创建所有城市的列表。< / p>

Answer 1

你可以做一个有条件的和。由于您没有提供任何样本数据，以下是您应该能够在您的案例中使用和使用的示例：

with sample_data as (select 1 id, 'a' val1, 10 val2 from dual union all
                     select 1 id, 'a' val1, 20 val2 from dual union all
                     select 1 id, 'b' val1, 30 val2 from dual union all
                     select 1 id, 'b' val1, 40 val2 from dual union all
                     select 1 id, 'c' val1, 50 val2 from dual union all
                     select 1 id, 'd' val1, 60 val2 from dual union all
                     select 1 id, 'e' val1, 70 val2 from dual union all
                     select 2 id, 'a' val1, 100 val2 from dual union all
                     select 2 id, 'b' val1, 200 val2 from dual union all
                     select 2 id, 'b' val1, 300 val2 from dual union all
                     select 2 id, 'c' val1, 400 val2 from dual union all
                     select 2 id, 'd' val1, 500 val2 from dual union all
                     select 2 id, 'd' val1, 600 val2 from dual union all
                     select 2 id, 'e' val1, 700 val2 from dual)
-- end of creating a subquery that mimics a table called sample_data with data in it.
select   id,
         count(*) total,
         count(case when val1 in ('a', 'b') then 1 end) total_a_b,
         count(case when val1 in ('c', 'd') then 1 end) total_c_d
from     sample_data
group by id;

        ID      TOTAL  TOTAL_A_B  TOTAL_C_D
---------- ---------- ---------- ----------
         1          7          4          2
         2          7          3          3

Answer 2

您可能需要条件聚合：

SELECT CITY,
       SUM(1) AS TotalResult,
       SUM(
           CASE WHEN RESULT IN ('A', 'B')
               THEN 1
               ELSE 0
           END) AS "Result= A or B",
       SUM(
           CASE
               WHEN RESULT IN ('C', 'D', 'E')
               THEN 1
               ELSE 0
           END
          )
           AS "Result= C or D or E",
       SUM(
           CASE
               WHEN RESULT = 'F'
               THEN 1
               ELSE 0
           END
          ) AS "Result= F"
  FROM Tbl1 t1 JOIN Tbl2 t2 ON t1.id = t2.code
  GROUP BY CITY

这在CITY子句中使用GROUP BY，因此为CITY的每个值提供一行;在同一行上，它使用CASE仅计算行匹配的情况。