通过使用数据库链接加入本地和外部数据库来更新记录

问题描述

1. t - 当前数据库表
2. table1 - 其他数据库
3. database - 存储“其他数据库”凭据的当前数据库表

SELECT 
    t.*
FROM "database" d,t,dblink_exec(
        format('dbname = %s host = %s port = %s user = %s password = %s',databasename,servername,port,username,"password"),format('UPDATE 
                            table1 a 
                       SET 
                           (col1,col2) = (SELECT
                                                %L :: json,Now() 
                                           FROM t b -- t is the local table (from current db) 
                                           WHERE b.col2 = a.col2 
                                               AND b.col3 = a.col3 
                                               AND b.col4 = a.col4)
                       WHERE a.col2 = ''ABC''
                            AND a.col3 = ''DEF''
                            ',data )) -- column data is from table ```t```
WHERE databasename = 'otherdb';

如何通过将本地表连接到其他数据库来更新记录。我需要将桌子 t 固定在正确的位置。我无法在其他数据库上运行它，因为还有其他依赖项（主要是时间）。

解决方法

我能够通过首先加入表并形成 UPDATE 语句并将 UPDATE 语句提供给 dblink_exec 来实现这一点。

SELECT
    dblink_exec(
        format('dbname = %s host = %s port = %s user = %s password = %s',databasename,servername,port,username,"password"),format ('UPDATE table1 %1$sSET col4 = %3$L :: json,%2$scol3 = now() %1$sWHERE col3 = %4$L %2$sAND col3 = ''ABC'' %2$sAND col2 = ''DEF'';',E'\n',E'\n\t',t.data,t.col3 
               )
    )
FROM t 
    INNER JOIN 
        (
            SELECT x.*
            FROM "database" d,dblink(
                            format('dbname = %s host = %s port = %s user = %s password = %s',"password"
                                    ),'SELECT 
                                * 
                            FROM  table1 
                            WHERE  col1 = ''ABC'' 
                                 AND col2 = ''DEF''
                                 '   
                         ) AS x( col1 TEXT,col2 TEXT,col3 TEXT,col4 TEXT
                                ) 
            WHERE databasename = 'otherdb'
        ) as otherdb
    CROSS JOIN "database" d
        ON otherdb.col1 = t.col1
            AND otherdb.col2 = t.col2
            AND otherdb.col1 = 'DEF'
            AND otherdb.col2 = 'ABC'
WHERE databasename = 'otherdb';