Lessons

What is SQL?

SQL (Structured Query Language) is a domain-specific programming language that handles table data. It was developed in the 1970s.
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SQL and Databases tracks
What is SQL?
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SQL Сonstraints
Lessons

SQL Сonstraints

Data type restrictions help us avoid a lot of mistakes, but sometimes these restrictions can be very specific.
SQL PRIMARY KEY constraint
Lessons

SQL PRIMARY KEY constraint

While some individuals may share the same name, their email addresses will differ, making it suitable to use this field as a unique key.
SQL FOREIGN KEY constraint
Lessons

SQL FOREIGN KEY constraint

How to use the foreign key constraint to connect two tables and manage the data stored there.
SQL Date Functions
Lessons

SQL Date Functions

SQL provides a wide variety of date and time types.
SQL GROUP BY statement
Lessons

SQL GROUP BY statement

Imagine that we need to compute an aggregate value not for the whole table or one specific category but rather for many separate categories.
SQL ORDER BY statement
Lessons

SQL ORDER BY statement

To specify the order of the resulting rows, use the ORDER BY clause in a query.