An inner join is a type of SQL statement used to join two or more tables together in a database. It is the most common type of join used in SQL queries and is used to combine rows from two or more tables that have related data in them.
An inner join is also known as an equi-join because it only returns rows that have matching values in both tables being joined. The syntax for an inner join in MySQL looks like this:
SELECT table1., table2.
FROM table1
INNER JOIN table2 ON table1.column_name = table2.column_name;
In this example, the two tables are being joined on a specific column (column_name). The “*” after each table indicates that all columns in those tables should be selected.
Inner joins can be used to retrieve data from multiple tables in one query. For instance, if you wanted to get information about customers and their orders from separate tables, you could use an inner join to join the tables on the customer ID column.
Inner joins can also be used to combine data from multiple tables in order to create more meaningful results. For example, if you wanted to know how many customers had placed orders over a certain amount in the past month, you could use an inner join to sum up the total orders from each customer in the month.
Inner joins are the most commonly used type of join in SQL. They are useful for combining data from multiple tables and are relatively easy to write. However, they have their limits and cannot be used for some types of more complex queries.
