如何根据sql中的某些条件连接两个表？

Question

我需要帮助来连接两个表以获得输出。我告诉你场景。你能帮帮我吗？

例子：

我有一个 sql 查询： 查询：

SELECT * 
FROM (
  SELECT schemaname ,objectname,usename,
         HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'select') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS sel,
         HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'insert') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS ins,
         HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'update') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS upd,
         HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'delete') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS del,
         HAS_TABLE_PRIVILEGE(usrs.usename, fullobj, 'references') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS ref 
  FROM (
     SELECT schemaname, 't' AS obj_type, tablename AS objectname, schemaname + '.' + tablename AS fullobj 
     FROM pg_tables 
     WHERE schemaname not in ('pg_internal') 
     UNION 
     SELECT schemaname, 'v' AS obj_type, viewname AS objectname, schemaname + '.' + viewname AS fullobj 
     FROM pg_views 
     WHERE schemaname not in ('pg_internal')
  ) AS objs,
  (SELECT * FROM pg_user) AS usrs ORDER BY fullobj
) 
WHERE (sel = true or ins = true or upd = true or del = true or ref = true) 
   and schemaname='medaff' 
   and usename not in ('rdsdb','clustersa','prdrscl01master') 
   and objectname in RES;

上面的查询给出了一些输出：

Table 1

schemaname  objectname   usename           sel  ins  upd  del  ref
medaff      dmn_category medaff_dev_admin  True True True True True
medaff      dmn_category emea_dev_admin    True True True True True
medaff      dmn_category cdeadmin          True True True True True

我有其他表有一些记录：

Table 2:

application_name  tablename
smart_source      dmn_category

如何连接这两个表以在最终输出中获取应用程序名称：

application_name schemaname  objectname   usename           sel  ins  upd  del  ref  
smart_source     medaff      dmn_category medaff_dev_admin  True True True True True
smart_source     medaff      dmn_category emea_dev_admin    True True True True True
smart_source     medaff      dmn_category cdeadmin          True True True True True

Answer 1

我认为这里的重点是您想将一个复杂的查询结果与另一个表连接起来？您可以通过以下方式实现：

1. 使用WITH tbl AS (.....)然后加入tbl上的另一个表（查询结果）。
2. 为您的第一个结果创建一个VIEW，然后将另一个表与该视图连接起来。

Answer 2

当您想表示 2 个表时，您可以使用 inner join on 但为此您需要在每个表中都有一些共同点。 例如：

select t.name, o.code from FirstTable t inner join OtherTable o on t.code = o.code

Answer 3

您的查询看起来不错。不过，UNION 应该是 UNION ALL，并且

) AS objs,
(SELECT * FROM pg_user) AS usrs

应该是

) AS objs
CROSS JOIN pg_user AS usrs

和

ORDER BY fullobj

是多余的，因为允许 DBMS 忽略子查询中的ORDER BY。 （如果您希望对结果进行排序，请在查询末尾添加 ORDER BY fullobj。）

但无论如何，你似乎想要的只是加入 table2：

) AS objs
CROSS JOIN pg_user AS usrs
INNER JOIN table2 ON table2.tablename = objs.objectname

完整的查询：

SELECT * FROM 
(
  SELECT
    table2.application_name,
    objs.schemaname,
    objs.objectname,
    usrs.usename,
    HAS_TABLE_PRIVILEGE(usrs.usename, objs.fullobj, 'select') AND has_schema_privilege(usrs.usename, objs.schemaname, 'usage') AS sel,
    HAS_TABLE_PRIVILEGE(usrs.usename, objs.fullobj, 'insert') AND has_schema_privilege(usrs.usename, objs.schemaname, 'usage') AS ins,
    HAS_TABLE_PRIVILEGE(usrs.usename, objs.fullobj, 'update') AND has_schema_privilege(usrs.usename, objs.schemaname, 'usage')  AS upd,
    HAS_TABLE_PRIVILEGE(usrs.usename, objs.fullobj, 'delete') AND has_schema_privilege(usrs.usename, objs.schemaname, 'usage')  AS del,
    HAS_TABLE_PRIVILEGE(usrs.usename, objs.fullobj, 'references') AND has_schema_privilege(usrs.usename, objs.schemaname, 'usage') AS ref
  FROM
  (
    SELECT 
      schemaname, 
      't' AS obj_type, 
      tablename AS objectname, 
      schemaname + '.' + tablename AS fullobj
    FROM pg_tables 
    WHERE schemaname not in ('pg_internal') 
    UNION ALL
    SELECT 
      schemaname, 
      'v' AS obj_type, 
      viewname AS objectname, 
      schemaname + '.' + viewname AS fullobj 
    FROM pg_views 
    WHERE schemaname not in ('pg_internal')
  ) AS objs
  CROSS JOIN pg_user AS usrs
  INNER JOIN table2 ON table2.tablename = objs.objectname
)
WHERE (sel = true or ins = true or upd = true or del = true or ref = true)
  and schemaname = 'medaff' 
  and usename not in ('rdsdb', 'clustersa', 'prdrscl01master')
ORDER BY schemaname, objectname, application_name, usename;