How does mysql implement table join (including left, right, inner, full join)

Mysql how to achieve table join (including left, right, inner, full join), first of all need to appear in the query of the join of two tables, the following examples to explain the differences between various join queries.

Table an and table b are shown below

Table a contains abcd

There is abcf in table b

Internal connection:

SELECT * from an INNER JOIN b on a.name=b.id

Get the result as shown in the figure, select the equivalent result (abc)

Left connection:

SELECT * from a left JOIN b on a.name=b.id

The query result is shown in the figure, and table an is selected as the benchmark. (abcd)

Right connection:

SELECT * from a right JOIN b on a.name=b.id

The query result is shown in the figure, and table an is selected as the benchmark. (abcf)

Full connection: mysql does not support full connection (full join), you can use left join+ union+right join

(SELECT * from a left JOIN b on a.name=b.id) UNION (SELECT * from a RIGHT JOIN b on a.name=b.id)

The result is that all are displayed, as shown in the following figure:

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