Shulou(Shulou.com)05/31 Report--

Editor to share with you SQL how to achieve multi-table join query, I hope you have something to gain after reading this article, let's discuss it together!

According to the connection mode, it can be divided into equal connection, unequal connection, external connection, self-connection, multi-table association, etc.

1. Equal connection

The traditional way of writing select A. Column, B. Column from Table A, Table B where A. Column name = B. Column name

SQL 1999 writing method

Natural join: will be conditional on the same column name in both tables

2. Unequal connection

Traditional writing method: a brief introduction

SQL 1999 writing method

3. External connection

3.1-definition of inner and outer connections

3.2-Writing method

Traditional writing (+)

SQL 1999 writing method

4. Self-connection

Table A connects with Table A.

5. Multi-table association

After reading this article, I believe you have a certain understanding of "how to achieve multi-table join query in SQL". If you want to know more about it, you are welcome to follow the industry information channel. Thank you for reading!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.