MySQL's various joins

These 5 joins are commonly used.

First join = INNER JOIN Here is a description: Click to open the link

Here, I don't need a table to illustrate, here's an example.

The simple thing is,

INNER JOIN: only if the relationship is selected, no null is present

The LEFT join and right join are a set of

Left join: With left table as the benchmark, all the data of the table will appear, and if there is no corresponding, the right table will be represented by NULL.

Right join: All data from the right table will appear, and if there is no corresponding, the left table is represented by NULL.

Full Join: is the left join and right join collection

Two tables of data will appear, the other table does not have corresponding data, are represented by null

MySQL's various joins