sql - 多个表上的多个 LEFT OUTER JOIN

Question

我想转换以下 Oracle SQL 查询语法(使用 LEFT OUTER JOIN 而不是 (+)):

SELECT      *
FROM        TABLEA A, TABLEB B, TABLEC C, TABLED D
WHERE       MY_COL = @col_val
AND         A.X = B.X(+)
AND         B.Y = C.Y(+)
AND         D.Z=A.Z

这是我到目前为止尝试过的:

SELECT *
FROM TABLEA A, TABLEB B, TABLEC C, TABLED D
LEFT OUTER JOIN TABLEA A ON A.X = B.X
LEFT OUTER JOIN TABLEC C ON B.Y = C.Y
WHERE MY_COL = @col_val
AND D.Z = A.Z;

但我收到错误:

"ORA-00904: "B"."X" : invalid identifier"

Answer 1

join在 D是内连接，其余是左外连接:

SELECT *
FROM TABLEA A JOIN
     TABLED D
     ON D.Z = A.Z LEFT JOIN
     TABLEB B
     ON A.X = B.X LEFT JOIN
     TABLEC C
     ON B.Y = C.Y 
WHERE MY_COL = @col_val;

我总是从内部连接开始连接链，然后是 left outer join .我从不使用 right join , 和 full join比较少。内部联接定义了结果集中的行，因此它们排在最前面。