如何在mysql中关联多表

我有5张桌子。是的

主表 子表1 子表2 子表3 子表4 这里，mainid是所有表的通用ID。我想在一页中显示所有表字段。。。在该页面中，我们将名称作为输入。。。每个表包含大约500万条记录

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如何有效地为上述情况编写查询？

如果您只想从所有表中选择所有字段，而不进行任何筛选，那么使用内部联接相对简单

例如

SELECT * FROM maintable INNER JOIN subtable1 ON subtable1.mainid = maintable.id INNER JOIN subtable2 ON subtable2.mainid = maintableid ... 

等

希望有帮助

SELECT
  mmaintable.colnames,
  subtable1.colnames,
  subtable2.colnames,
  subtable3.colnames,
  subtable4.colnames
FROM maintable
  LEFT JOIN subtable1
    ON subtable1.mainid = maintable.id
  LEFT JOIN subtable2
    ON subtable2.mainid = maintable.id 
      LEFT JOIN subtable3
    ON subtable3.mainid = maintable.id 
      LEFT JOIN subtable4
    ON subtable4.mainid = maintable.id 

id int(11)=>primary key auto increment,
mainid int(11),
field3 varchar(255),
field4 varchar(255)

id int(11)=>primary key auto increment,
mainid int(11),
field5 varchar(255),
field6 varchar(255)

id int(11)=>primary key auto increment,
mainid int(11),
field7 varchar(255),
field8 varchar(255)

SELECT * FROM maintable INNER JOIN subtable1 ON subtable1.mainid = maintable.id INNER JOIN subtable2 ON subtable2.mainid = maintableid ... 

SELECT
  mmaintable.colnames,
  subtable1.colnames,
  subtable2.colnames,
  subtable3.colnames,
  subtable4.colnames
FROM maintable
  LEFT JOIN subtable1
    ON subtable1.mainid = maintable.id
  LEFT JOIN subtable2
    ON subtable2.mainid = maintable.id 
      LEFT JOIN subtable3
    ON subtable3.mainid = maintable.id 
      LEFT JOIN subtable4
    ON subtable4.mainid = maintable.id