unions

n. Union(??? ?? ??); Marriage

all

English [?l]

adj. ??, ??? ?

?? ?, ?? ??

n. , ??, ??, ?? ?] (????) ??? ?? ?? ?

SQLite UNION ALL ?? ???

Role: UNION ALL ???? ?? ?? ???? ? ?? SELECT ?? ??? ???? ? ?????.

UNION? ???? ??? ??? UNION ALL ????? ?????.

??: ??UNION ALL? ?? ??? ??? ????.

SELECT ??1 [, ??2 ]
FROM table1 [, table2 ]
[WHERE ??]

UNION ALL

SELECT ??1 [, ??2 ]
FROM table1 [, table2 ]
[WHERE ??]

??? ??? ??? ??? ?? ?? ??? ?????.

SQLite UNION ALL ?? ?

讓我們使用 SELECT 語(yǔ)句及 UNION ALL 子句來連接兩個(gè)表，如下所示：

sqlite> SELECT EMP_ID, NAME, DEPT FROM COMPANY INNER JOIN DEPARTMENT
        ON COMPANY.ID = DEPARTMENT.EMP_ID
   UNION ALL
     SELECT EMP_ID, NAME, DEPT FROM COMPANY LEFT OUTER JOIN DEPARTMENT
        ON COMPANY.ID = DEPARTMENT.EMP_ID;
這將產(chǎn)生以下結(jié)果：

EMP_ID      NAME                  DEPT
----------  --------------------  ----------
1           Paul                  IT Billing
2           Allen                 Engineerin
3           Teddy                 Engineerin
4           Mark                  Finance
5           David                 Engineerin
6           Kim                   Finance
7           James                 Finance
1           Paul                  IT Billing
2           Allen                 Engineerin
3           Teddy                 Engineerin
4           Mark                  Finance
5           David                 Engineerin
6           Kim                   Finance
7           James                 Finance