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This article introduces the knowledge of "A brief introduction to arrays in PostgreSQL". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

If you buy something on a website, the information you buy can be expressed in the following table:

CREATE TABLE purchases (id integer NOT NULL, user_id integer, items decimal (10pm 2) [100] [1], occurred_at timestamp)

In this table, you have an array field to maintain multiple product records, including:

The number of the goods purchased.

Quantity

Price

The SQL to insert data into this table is as follows:

INSERT INTO purchases VALUES (1,37,'{{15.0,1.0,25.0}, {15.0,1.0,25.0}', now ())

INSERT INTO purchases VALUES (2,2,'{{11.0,1.0,4.99}}', now ())

A more practical example is the use of tags, where you can use tags to identify items you buy:

CREATE TABLE products (id integer NOT NULL, title character varying, description text, tags text [], price numeric (10Magne2))

You can use basic query statements to get data:

SELECT title, unnest (tags) items FROM products

You can also use Postgres's Gin and Gist index to quickly search for products based on specified tags:

-- Search where product contains tag ids 1 AND 2SELECT * FROM productsWHERE tags @ > ARRAY [1,2]-- Search where product contains tag ids 1 OR 2SELECT * FROM productsWHERE tags & & ARRAY [1,2] "A brief introduction to arrays in PostgreSQL" ends here. Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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