几张图解释它们之间的区别
1、inner join
\1.gif
用法：
SELECT column_name(s)
FROM table1
JOIN table2
ON table1.column_name=table2.column_name;
2、left join
\2.gif
用法：
SELECT column_name(s)
FROM table1
LEFT JOIN table2
ON table1.column_name=table2.column_name;
3、right join
\3.gif
用法：
SELECT column_name(s)
FROM table1
RIGHT JOIN table2
ON table1.column_name=table2.column_name;
4、full outer join
\4.gif
用法：
SELECT column_name(s)
FROM table1
FULL OUTER JOIN table2
ON table1.column_name=table2.column_name;
其他注意事项
- laravel 中默认join为inner join
参考网站
