Typical queries in the SELECT * FROM table format are sometimes not enough. When the data for a query is not in one table, but in several, or when it is necessary to specify several selection parameters at once, you will need more sophisticated queries.

This article will explain how to build such queries and provide examples of complex SQL queries.

What Does a Complex Query Look Like?

First, let’s define the conditions for composing the SQL query. In particular, you will need to use the following selection parameters:

• the names of the tables from which you want to extract data;
• the values of fields that must be returned to the original ones after making changes to the database;
• the relationships between tables;
• the sampling conditions;
• the auxiliary selection criteria (restrictions, ways of presenting information, type of sorting).

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