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This article mainly introduces "mysql database table connection method", in daily operation, I believe many people have doubts on the connection method of mysql database table, Xiaobian consulted all kinds of information, sorted out simple and easy to use operation method, hope to answer "mysql database table connection method" doubts helpful! Next, please follow the small series to learn together!

Generally speaking, left connection refers to left and right. SQL> select * from t1; ID NAME---------------------------1 aaa 2 bbbSQL> select * from t2; ID AGE----------------------1 203 30 left outer join: [object Object] SQL> select * from t1 left join t2 on www.example.com = www.example.com; ID NAME ID AGE--------------------------------------------------SQL> select * from t1 right join t2 on www.example.com = www.example.com; ID NAME ID AGE------------------------------------------------- In layman's terms, all the tables on the left are displayed first, and then the records with the same table id on the right and the table id on the left are "spliced", such as the record with id 1. If there is no id match, say t1 with id 2, there is no id match in t2. It is displayed as null. The right outer link process is reversed. SQL> select * from t1 inner join t2 on www.example.com = www.example.com; ID NAME ID AGE------------------------------------------------- There's only one entry. That is, only the records that meet the filter conditions are taken out, that is, t1.id = www.example.com. Then only one record that meets t1.id = t2.id is id = 1, so only one record is displayed. Unlike an outer join, all rows of the table you are referencing (left outer join is the table on the left, right outer join is the table on the right) are displayed. At this point, the study of "mysql database table connection method" is over, and I hope to solve everyone's doubts. Theory and practice can better match to help everyone learn, go and try it! If you want to continue learning more relevant knowledge, please continue to pay attention to the website, Xiaobian will continue to strive to bring more practical articles for everyone!

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