Mysql 左连接未按预期工作

Question

我正在尝试一个简单的左连接，但这给我带来了问题。我需要列出的所有客户(表 a)，无论他们在特定日期范围内是否有发票(表 b)。我的两次尝试都获得了该期间唯一拥有发票的客户:

select b.clientname,a.* from invdata a
   left join clidata b on a.clidataid=b.recordid
      where b.recstatus=1 and b.isactive=1
      and a.reccreate between '2015-04-01 00:00:00' and '2015-04-30 23:59:59';

或者

select a.clientname,b.* from clidata a
   left join invdata b on a.recordid=b.clidataid
      where a.recstatus=1 and a.isactive=1
      and b.reccreate between '2015-04-01 00:00:00' and '2015-04-30 23:59:59';

请提供一点帮助。谢谢!!

Answer 1

与where条件的左连接是内连接，会根据where条件过滤数据，您可能需要将where条件移至连接条件

  select b.clientname,a.* from invdata a
  left join clidata b on a.clidataid=b.recordid
  and b.recstatus=1 and b.isactive=1
  and a.reccreate between '2015-04-01 00:00:00' and '2015-04-30 23:59:59';