MySQL在使用左联接时复制列值

我有表格并插入：

CREATE TABLE IF NOT EXISTS `klik_zona` (
  `kode_zona` int(10) unsigned NOT NULL,
  `klik` int(10) unsigned NOT NULL,
  PRIMARY KEY (`kode_zona`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `klik_zona` (`kode_zona`, `klik`) VALUES
(1, 45);

CREATE TABLE IF NOT EXISTS `tampil_zona` (
  `kode_zona` int(10) unsigned NOT NULL,
  `tanggal` date NOT NULL,
  `tampil` int(10) unsigned NOT NULL,
  PRIMARY KEY (`kode_zona`,`tanggal`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `tampil_zona` (`kode_zona`, `tanggal`, `tampil`) VALUES
(1, '2014-03-16', 100),
(1, '2014-03-17', 23);

CREATE TABLE IF NOT EXISTS `zona_iklan` (
  `kode_zona` int(10) unsigned NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`kode_zona`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ;

INSERT INTO `zona_iklan` (`kode_zona`) VALUES
(1),
(2),
(3);

我有一个疑问如下：

SELECT z.kode_zona, SUM( tz.tampil ) , SUM( kz.klik )
FROM zona_iklan z
LEFT JOIN tampil_zona tz ON tz.kode_zona = z.kode_zona
LEFT JOIN klik_zona kz ON kz.kode_zona = z.kode_zona
GROUP BY z.kode_zona

但它给出了结果：

kode_zona   SUM(tz.tampil)  SUM(kz.klik)    
1                123        90
2                NULL      NULL
3                NULL      NULL

我希望得到结果：

kode_zona   SUM(tz.tampil)  SUM(kz.klik)    
1                123        45
2                NULL      NULL
3                NULL      NULL

谁能帮帮我吗。如何进行查询，使其显示为我希望得到的结果

谢谢。

尝试以下查询：

SELECT distinct z.kode_zona, SUM(distinct tz.tampil ) , SUM(distinct kz.klik )
FROM zona_iklan z
LEFT JOIN tampil_zona tz ON z.kode_zona = tz.kode_zona 
LEFT JOIN klik_zona kz ON z.kode_zona = kz.kode_zona
GROUP BY z.kode_zona

我想，这就是你想要的

select kode_zona,
       sum(case when splitter = 'tampil' then summer else 0 end) as sum_tampil,
       sum(case when splitter = 'klik' then summer else 0 end) as sum_klik
  from (SELECT 'tampil' as splitter, z.kode_zona, SUM(tz.tampil) as summer
          FROM zona_iklan z
          LEFT JOIN tampil_zona tz
            ON tz.kode_zona = z.kode_zona
         GROUP BY z.kode_zona
        union all
        SELECT 'klik' as splitter, z.kode_zona, SUM(kz.klik) as summer
          FROM zona_iklan z
          LEFT JOIN klik_zona kz
            ON kz.kode_zona = z.kode_zona
         GROUP BY z.kode_zona) x
 group by kode_zona

SQL小提琴测试：

另一个想法

SELECT x.kode_zona
     , y.type
     , COALESCE(SUM(y.value),0) ttl
  FROM zona_iklan x
  LEFT
  JOIN 
     ( SELECT kode_zona, 'klik' type, klik value FROM klik_zona
       UNION
       SELECT kode_zona, 'tampil' , tampil value FROM tampil_zona
     ) y
    ON y.kode_zona = x.kode_zona
 GROUP
    BY x.kode_zona
     , y.type;

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使用group by避免重复添加

（1，'2014-03-18'，23），不会给出正确的结果（仍然是123，应该是146）。当我将insert table更改为：