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

这是我到目前为止所尝试的内容：

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：

＆＃34; ORA-00904：＆＃34; B＆＃34;。＆＃34; X＆＃34; ：无效的标识符＆＃34;

Answer 1

join上的D是内联接，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;

我总是使用内部联接开始连接链，然后是left outer join。我从不使用right join和full join。内部联接定义结果集中的行，因此它们首先出现。

Answer 2

你不应该混合显性和隐性的sintax

  SELECT *
  FROM TABLEA A 
  INNER JOIN TABLEL L ON L.Z = A.Z
  LEFT OUTER JOIN TABLEB B ON A.X = B.X
  LEFT OUTER JOIN TABLEC C ON B.Y = C.Y
  WHERE A.MY_COL = @col_val

你应该使用TABLEL的内连接（或连接）

Answer 3

试试这个：

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

TABLEB和TABLEC进入LEFT OUTER JOIN（您使用了+），而TABLED进入INNER JOIN

多个表上的多个LEFT OUTER JOIN

3 个答案: