有没有办法改进这个查询

Posted 2023-04-15

【中文标题】有没有办法改进这个查询

【英文标题】：Is there a way to improve more this query

【发布时间】：2020-09-28 14:25:07

【问题描述】：

我一直在学习如何使用内部联接，所以我修改了以下查询以使用内部联接，但我在查询的最后一个片段遇到问题，是否可以在那里使用内部联接？我遇到了麻烦，因为“MOV”是在这个片段之前完成的查询......有人可以帮我理解如何在那里使用吗？以下查询有效，只是尽可能地改进它们

片段：

FROM   TBLMOVOBLIGACIONES MOV1
                                  WHERE MOV1.STRMOVANOMES = :periodo
                                   AND  MOV1.STRCLINIT = MOV.STRCLINIT
                                   AND  MOV1.STROBLOBLIGSARC = MOV.STROBLOBLIGSARC

完整查询：

SELECT * FROM (

 

SELECT MOV.NUMPROCODIGO APLICATIVO,
       MOV.STRCLINIT NIT,
       CL.STRCLINOMBRE CLIENTE,
       MOV.STROBLOBLIGSARC OBLIGACION,
       MOV.NUMMOVVLRCAPCREDITO + MOV.NUMMOVVLRINTCREDI + MOV.NUMMOVVLRCAPOTRO SALDO_OBL,
       MOV.NUMMOVTIPOCREDITO TIPO_CREDITO,
       MOV.NUMMOVNRODIASCAP DIAS_CAP,
       MOV.NUMMOVNRODIASINT DIAS_INT,
       MOV.STRMOVCALIFEDAD,
       CASE 
        WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=0 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 30 THEN 'A'
        WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=31 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 90 THEN 'B'
        WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=91 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 180 THEN 'C'
        WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=181 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 360 THEN 'D'
        WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=361 THEN 'E'
       END AS CALIFEDAD_REAL
FROM TBLMOVOBLIGACIONES MOV INNER JOIN TBLCLIENTES CL ON MOV.STRCLINIT = CL.STRCLINIT 
WHERE MOV.STRMOVANOMES = :periodo
 AND  MOV.NUMPROCODIGO NOT IN (24)
 AND MOV.NUMMOVVLRCAPCREDITO + MOV.NUMMOVVLRINTCREDI + MOV.NUMMOVVLRCAPOTRO > 0
 AND  MOV.NUMMOVTIPOCREDITO = 1
 AND  NVL(MOV.STRMOVCALIFEDAD,'N') != (SELECT CASE 
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=0 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 30  THEN 'A'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=31 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 90 THEN 'B'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=91 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 180 THEN 'C'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=181 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 360 THEN 'D'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=361 THEN 'E'
                                     END AS CALIF_CALC
                              FROM   TBLMOVOBLIGACIONES MOV1
                              WHERE MOV1.STRMOVANOMES = :periodo
                               AND  MOV1.STRCLINIT = MOV.STRCLINIT
                               AND  MOV1.STROBLOBLIGSARC = MOV.STROBLOBLIGSARC)

【问题讨论】：

每个帖子只问一个问题 - 这样更容易回答。另外，您能否发布 DDL、示例数据和预期结果，最好使用 dbfiddle？最后，您想要实现什么 - 您是想让代码“更好”，还是有性能问题？

要查看哪个查询？完全被这个问题迷失了。

对不起，我将问题简化为仅需要帮助改进的主要查询，我试图使其具有更好的性能并且看起来更好，但主要是如何使用内部连接查询的最后一个片段

将最后一个片段转换为使用内连接没有意义（请参阅@MatthewMcPeak 的回答），而且它可能不会大大提高性能。

【参考方案1】：

我会质疑你的这部分问题：

 AND  NVL(MOV.STRMOVCALIFEDAD,'N') != (SELECT CASE 
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=0 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 30  THEN 'A'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=31 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 90 THEN 'B'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=91 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 180 THEN 'C'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=181 AND GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) <= 360 THEN 'D'
                                      WHEN GREATEST(NVL(MOV1.NUMMOVNRODIASCAP,0), NVL(MOV1.NUMMOVNRODIASINT,0)) >=361 THEN 'E'
                                     END AS CALIF_CALC
                              FROM   TBLMOVOBLIGACIONES MOV1
                              WHERE MOV1.STRMOVANOMES = :periodo
                               AND  MOV1.STRCLINIT = MOV.STRCLINIT
                               AND  MOV1.STROBLOBLIGSARC = MOV.STROBLOBLIGSARC)

(strmovanomes, strclinit, stroblobligsarc) 要么包含（或完全是）tblmovobligaciones 的主键，要么不包含。

如果确实，则子查询正在从tblmovobligaciones 查询您已经拥有的同一行。在这种情况下，应删除子查询并将条件替换为：

 AND  NVL(MOV.STRMOVCALIFEDAD,'N') != CASE 
                                      WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=0 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 30  THEN 'A'
                                      WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=31 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 90 THEN 'B'
                                      WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=91 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 180 THEN 'C'
                                      WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=181 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 360 THEN 'D'
                                      WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=361 THEN 'E'
                                     END

如果它没有那么是什么阻止该子查询返回多行（这会在运行时导致错误）？

您也可以一次性选择那个大表达式并重复使用它。这是一个偏好问题。看起来像这样：

SELECT MOV.NUMPROCODIGO APLICATIVO,
       MOV.STRCLINIT NIT,
       CL.STRCLINOMBRE CLIENTE,
       MOV.STROBLOBLIGSARC OBLIGACION,
       MOV.NUMMOVVLRCAPCREDITO + MOV.NUMMOVVLRINTCREDI + MOV.NUMMOVVLRCAPOTRO SALDO_OBL,
       MOV.NUMMOVTIPOCREDITO TIPO_CREDITO,
       MOV.NUMMOVNRODIASCAP DIAS_CAP,
       MOV.NUMMOVNRODIASINT DIAS_INT,
       MOV.STRMOVCALIFEDAD,
       mov.califedad_real_expr CALIFEDAD_REAL
FROM ( SELECT mov.*,
              CASE 
                WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=0 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 30 THEN 'A'
                WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=31 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 90 THEN 'B'
                WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=91 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 180 THEN 'C'
                WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=181 AND GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) <= 360 THEN 'D'
                WHEN GREATEST(NVL(MOV.NUMMOVNRODIASCAP,0), NVL(MOV.NUMMOVNRODIASINT,0)) >=361 THEN 'E'
              END AS califedad_real_expr
        FROM TBLMOVOBLIGACIONES MOV) MOV 
INNER JOIN TBLCLIENTES CL ON MOV.STRCLINIT = CL.STRCLINIT 
WHERE MOV.STRMOVANOMES = :periodo
 AND  MOV.NUMPROCODIGO NOT IN (24)
 AND MOV.NUMMOVVLRCAPCREDITO + MOV.NUMMOVVLRINTCREDI + MOV.NUMMOVVLRCAPOTRO > 0
 AND  MOV.NUMMOVTIPOCREDITO = 1
 AND  NVL(MOV.STRMOVCALIFEDAD,'N') != mov.califedad_real_expr

（假设我对不必要的子查询是正确的）