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What is an inner join?

烟雨青岚

Jun 16, 2020 pm 04:42 PM

inner join

What is an inner join?

#What is an inner join?

Inner connection is also called connection, which is the earliest kind of connection. It can also be called a normal join or a natural join. An inner join deletes all rows from the result table that do not match rows in other joined tables, so the inner join may lose information.

The syntax of inner join is as follows:

select fieldlist from table1 [inner] join table2 on table1.column=table2.column

Select "=" in the "Set Association Between Tables" interface, which is an inner connection.

A connection in which a certain data item in two tables (or connections) is equal is called an inner connection. The result of the join is a new data table.

The status of the tables (or connections) participating in the connection in the inner connection is equal.

The order of operations for inner joins is:

1. Each column in the participating data table (or connection) is related to the columns of other data tables (or connections) Match to form a temporary data table;

2. Select records that satisfy equal data items from the temporary data table.

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