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What is SQL?
SQL, or Structured Query Language, is a programming language used to manage and manipulate data in a relational database.
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SQL and Databases tracks
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SQL Сonstraints
Data type restrictions help us avoid a lot of mistakes, but sometimes these restrictions can be very specific.
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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.
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SQL FOREIGN KEY constraint
How to use the foreign key constraint to connect two tables and manage the data stored there.
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SQL Date Functions
SQL provides a wide variety of date and time types.
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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.
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SQL ORDER BY statement
To specify the order of the resulting rows, use the ORDER BY clause in a query.
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