mysql基本操作【重要】_MySQL

 

 

 

补充:

连接查询的例

1.三个表的显示内连接:

SELECT
  a.*,
  b.*,
  c.*
FROM exampaper a
  INNER JOIN bigquestion b
  INNER JOIN exampaperquestion c
    ON a.paperId = b.paperId
      AND b.bigQuertionId = c.bigQuertionId

 

2.两个表的显示内连接

SELECT a.*,b.* FROM a INNER JOIN b ON a.age=b.ageB

 

3.将查到的数据作为一个虚表连接查询:

mysql> select id,name from user inner join (select class_id from class where cal
ss_name='3') as c on c.class_id=user.class_id;

 

 

　　

 

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