About mysql implementation of table join (left, right, inner, full join)

mysql implements table connection (left, right, inner, full join)

The connection between two tables appears in the query. The following uses examples to explain the differences between various connection queries

Table a, and table b are as shown below

a has abcd in the table

## b has abcf

in the table

Inner join:

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

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

Left join:

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

The query results are as shown in the figure, select table a as the benchmark. (abcd)

Right join:

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

The query results are as shown in the figure, select table a as the benchmark. (abcf)

Full join: mysql does not support full join (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 below:

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https://www.php.cn/course/list/51.html

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