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This article introduces how to execute SELECT statements on multiple tables in the Oracle database, the content is very detailed, interested friends can refer to, I hope it can be helpful to you.

Suppose you want to see the name of the product, and your colleague also wants to display the name of the product type in the same output. Now you know that the product name is saved in the column in the products table, and the second product type name is saved in the name column of the product_types table. The products table and product_types are associated with each other through a foreign key product_type_id, where the product_type_id column in the products table points to the product_type_id column in the product_ types table. So if you select the name and product_type_id columns of the product from the products table, the results should look like this:

SELECT name,product_type_id

FROM products

WHERE product_id=1

If you are retrieving the name column with product_type_id 1 from the product_types table, the result should look like this:

SELECT name,product_type_id

FROM product_types

WHERE product_type_id=1

You can see from the above results that product # 1 is a book. There's nothing complicated so far, but what should we do to see the name of the product and the type name of the product on the same line?

The answer is to join two tables in a query table. Joining two tables means that colleagues need to specify two tables in the FROM clause of the query, and then specify the related columns of the two tables (such as the foreign key in one table and the primary key in the other table). You can also use operators in the WHERE clause of a query. It is also important to note that the FROM clause of the SELECT statement must contain the table where the columns to be used in the join are located, and the columns used in the join are usually associated with foreign keys.

Therefore, according to the function that needs to be implemented, the SELECT clause is in the following format:

SELECT products.name,product_types.name

FROM products,product_types

WHERE products.product_type_id=product_types.product_type_id

On the Oracle database on how to execute SELECT statements on multiple tables to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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