用XOR语句加入子句 [英] Join Clause With a XOR Statement

问题描述

我正在加入一个连接，但似乎无法使此XOR正常工作.

I am doing a join and I can't seem to make this XOR to properly work.

SELECT t1.COMPANY, t1.MILES,
   CASE WHEN t2.MILES IS NULL THEN t3.MILES
        ELSE t2.MILES
   END AS MILES2,
   CASE WHEN t2.MILES = t1.MILES AND t2.MILES != 9999 THEN t2.FLATRATE
        ELSE t3.RATEBASIS
   END AS RATE           
FROM TABLE1 AS t1
    LEFT JOIN TABLE2 AS t2 
        ON t1.[COMPANY] = t2.[COMPANYCODE] AND (t1.[MILES] = t2.[MILES])
    INNER JOIN (
         SELECT TOP 1 TRUCKERCODE, MILES, RATEBASIS, FLATRATE FROM TABLE2 WHERE MILES = 9999
               ) AS t3 
   ON t1.[COMPANY] = t3.[COMPANYCODE]

如果里程数相同，我需要加入ON子句，然后获取匹配的给定字段，否则我需要从第二个表中获取的默认数据是里程数等于9999的位置.子句我得到了很多额外的行，其中MILES等于45，它从TABLE2读取了英里等于45的数据，并从所有数据得到了Miles等于9999.我需要它做一个或另一个，但不能同时做.这就是我的桌子的样子

I need the ON clause to join if the miles are the same then get the given fields that match otherwise the default data I need to get out of the second table is where the miles is equal to 9999. Right now with that ON clause I get many extra rows where the MILES equals lets say 45, it gets the data from TABLE2 where miles equals 45 and all the data where miles equals 9999. I need it to do one or the other but not both. This is what my tables would look like

TABLE1                          TABLE2
ID COMPANY MILES ETC            ID COMPANYCODE MILES RATE
1  ILLINI  50                   1  ILLINI      50    3.2
2  ILLINI  110                  2  ILLINI      110   5.2
3  ILLINI  150                  3  ILLINI      150   2.4
4  ILLINI  200                  4  ILLINI      200   1.9
5  ILLINI  250                  5  ILLINI      9999  1.5
6  ILLINI  300                       
7  ILLINI  350
8  ILLINI  400
9  ILLINI  450
10 ILLINI  500

Desired Output
COMPANY MILES MILES2 RATE
ILLINI  50    50    3.2
ILLINI  110   110   5.2
ILLINI  150   150   2.4
ILLINI  200   200   1.9
ILLINI  250   9999  1.5
ILLINI  300   9999  1.5                    
ILLINI  350   9999  1.5
ILLINI  400   9999  1.5
ILLINI  450   9999  1.5
ILLINI  500   9999  1.5

推荐答案

我认为这会为您提供想要的东西:

I think this will give you what you want:

SELECT t1.COMPANY, t1.MILES,
       CASE WHEN t2.MILES IS NULL THEN t3.MILES
            ELSE t2.MILES
       END AS MILES2,
       CASE WHEN t2.MILES IS NULL THEN t3.RATE
            ELSE t2.RATE
       END AS RATE           
FROM TABLE1 AS t1
LEFT JOIN TABLE2 AS t2 
   ON t1.[COMPANY] = t2.[COMPANYCODE] AND (t1.[MILES] = t2.[MILES])
INNER JOIN (
   SELECT TOP 1 COMPANYCODE, MILES, RATE FROM TABLE2 WHERE MILES = 9999
) AS t3 
   ON t1.[COMPANY] = t3.[COMPANYCODE]    

如果MILES中存在匹配项，则输出包含来自TABLE1，TABLE2的两条记录.否则，输出将包含左表中的记录，即TABLE1和TABLE2中带有MILES = 9999的 specific 记录.

If there is a match in MILES, then output contains both records from TABLE1, TABLE2. Otherwise, output contains record from left table, i.e. TABLE1 and the specific record from TABLE2 with MILES = 9999.

请注意，以防万一TABLE2中存在多个具有MILES = 9999的记录的情况，在最后一个子查询中使用TOP 1.

Please note that TOP 1 is used in the last sub-query just in case more than one records with MILES = 9999 exist in TABLE2.

输出:

COMPANY MILES   MILES2  RATE
----------------------------
ILLINI  50      50      3,2
ILLINI  110     110     5,2
ILLINI  150     150     2,4
ILLINI  200     200     1,9
ILLINI  250     9999    1,5
ILLINI  300     9999    1,5
ILLINI  350     9999    1,5
ILLINI  400     9999    1,5
ILLINI  450     9999    1,5
ILLINI  500     9999    1,5

此处是SQL Fiddle演示

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