更改+命令为+领导

Question

我正在尝试找到最有选择性的标准来开始加入 SQL。

我试过这个：

SELECT /*+ ordered */ 
  r3.object_id
FROM nc_references src
    INNER JOIN nc_objects     o ON o.object_type_id = 9146598858613093106
                               AND o.object_class_id = 90000330 
                               AND src.object_id = o.object_id
                               AND src.reference = 9155224548713314821
                               AND src.attr_id = 90100080 
    INNER JOIN nc_params      p ON ( p.list_value_id = 90100071  OR p.list_value_id = 90100072 )
                              AND p.object_id = o.object_id
                              AND p.attr_id = 90100070 
    INNER JOIN nc_po_actions  poa ON poa.manual_task_id = o.object_id
    INNER JOIN nc_po_tasks    pot ON pot.task_id = poa.task_id
    INNER JOIN nc_references  r1 ON r1.object_id = pot.container_id
                                   AND r1.attr_id = 9145923960313063683 
    INNER JOIN nc_references  r2 ON r2.object_id = pot.container_id
                                   AND r2.attr_id = 9145685312013687931 
    INNER JOIN nc_references  r3 ON r2.reference = r3.object_id
                                   AND r3.attr_id = 9145065302013613216 
                                   AND r1.reference = r3.reference
                     ;

但是这个 + ordered 已被弃用。如何使用 + leading?

实现此查询

Answer 1

使用前导提示并按照您希望数据库加入它们的顺序将 table 别名放在括号之间，例如：

SELECT /*+ leading(src o p poa) */ 
  r3.object_id
FROM nc_references src
INNER JOIN nc_objects     o ON o.object_type_id = 9146598858613093106
                           AND o.object_class_id = 90000330 
                           AND src.object_id = o.object_id
                           AND src.reference = 9155224548713314821
                           AND src.attr_id = 90100080 
INNER JOIN nc_params      p ON ( p.list_value_id = 90100071  OR p.list_value_id = 90100072 )
                          AND p.object_id = o.object_id
                          AND p.attr_id = 90100070 
INNER JOIN nc_po_actions  poa ON poa.manual_task_id = o.object_id
INNER JOIN nc_po_tasks    pot ON pot.task_id = poa.task_id
INNER JOIN nc_references  r1 ON r1.object_id = pot.container_id
                               AND r1.attr_id = 9145923960313063683 
INNER JOIN nc_references  r2 ON r2.object_id = pot.container_id
                               AND r2.attr_id = 9145685312013687931 
INNER JOIN nc_references  r3 ON r2.reference = r3.object_id
                               AND r3.attr_id = 9145065302013613216 
                               AND r1.reference = r3.reference
                 ;

这会告诉数据库从 src (nc_references) 开始，然后是 o (nc_objects)，等等

更改+命令为+领导

Change + ordered to + leading

sql

oracle

oracle11g