关于select的Oracle case语句

Question

尝试使用它的列在select语句上使用条件。我该怎么写这样的东西？

SELECT * FROM ( CASE (SELECT date_term, e_status 
                             FROM HM
                             WHERE c_num = 2327
                               AND e_unique = 'something')
                       WHEN (date_term) < TRUNC(SYSDATE)
                               OR (e_status IS NOT NULL OR e_status <> 'A')
                       THEN (SELECT NULL AS A,
                                    NULL AS B,
                                    NULL AS C,
                                    NULL AS D,
                                    NULL AS E,
                                    NULL AS F
                             FROM DUAL)
                       ELSE (SELECT p_val, p_type
                             FROM I_PARM T
                             WHERE c_num=2327
                             )
                             PIVOT 
                             (
                             MIN(p_val)
                             FOR p_type IN ('A1' AS A,
                                                    'B2' AS B,
                                                    'C3' AS C,
                                                    'D4' AS D,
                                                    'E5' AS E,
                                                    'F6' AS F)
                                                    )
                END);

• 更新整个查询比原始查询复杂一点。

我的右括号错误。感谢。

Answer 1

SELECT case when x.a = 'something' then b.y
       else c.z end
FROM X JOIN Y on x.somecol = y.somecol
JOIN Z on x.somecol = z.somecol;

你在问题​​中的方式是错误使用案例。用适当的列名替换join条件，因为您似乎从不同的表中选取值。