Lessons
Lessons

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 and Databases tracks
3
 min read
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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.
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SQL and Databases tracks
3
 min read
SQL FOREIGN KEY constraint
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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 and Databases tracks
3
 min read
SQL Date Functions
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SQL Date Functions

SQL provides a wide variety of date and time types.
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SQL and Databases tracks
3
 min read
SQL GROUP BY statement
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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 and Databases tracks
3
 min read
SQL ORDER BY statement
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SQL ORDER BY statement

To specify the order of the resulting rows, use the ORDER BY clause in a query.
by 
SQL and Databases tracks
3
 min read
SQL INSERT INTO statement
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SQL INSERT INTO statement

Use the INSERT INTO statement to insert a new record into a table with a simple query.
by 
SQL and Databases tracks
3
 min read