mysql - 查询多张表，但只得到一张表的结果，不重复

Question

这是一个解释我需要什么的例子:

我有 3 张 table :

 contact: { id, invoices, name } // a contact can have several invoices
 invoice: { id, contact, lines, comment } // an invoice can have several lines but only one contact
 line: { id, invoice, designation } // a line can have only one invoice

如果用户搜索发票，则希望查询注释、名称和名称字段并仅获取匹配的发票。

所以我这样做了:

SELECT 
  invoice.id AS id, 
  invoice.contact AS contact, 
  invoice.comment AS comment, 
FROM invoice 
  LEFT JOIN contact ON invoice.contact = contact.id 
  LEFT JOIN line ON line.invoice = invoice.id
WHERE (
  contact.name LIKE '%SEARCH_TERM%' OR 
  invoice.comment LIKE '%SEARCH_TERM%' OR 
  line.designation LIKE '%SEARCH_TERM%'
)

此工作正常，但如果发票有多行与搜索词匹配，我将获得多次相同的发票。

所以我的问题是:即使在多个相关记录中找到搜索词，是否有办法只获取一次发票？

此外，有没有办法只获取发票的字段而不使用 ALIAS(除了搜索之外，我不关心表联系人和行)？

如果您知道更好的方法，我很想听听。

Answer 1

SELECT 
  DISTINCT invoice.*
FROM invoice 
  LEFT JOIN contact ON invoice.contact = contact.id 
  LEFT JOIN line ON line.invoice = invoice.id
WHERE (
  contact.name LIKE '%SEARCH_TERM%' OR 
  invoice.comment LIKE '%SEARCH_TERM%' OR 
  line.designation LIKE '%SEARCH_TERM%'
)