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SQL Database Fundamentals
Learn essential SQL queries and database concepts
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Card 1
What is SQL?
SQL (Structured Query Language) is a standard language for managing and manipulating relational databases.
Card 2
What is the difference between WHERE and HAVING?
WHERE filters rows before grouping, cannot use aggregate functions. HAVING filters groups after GROUP BY, can use aggregate functions.
Card 3
What are the different types of JOIN?
INNER JOIN (matching rows), LEFT JOIN (all left + matching right), RIGHT JOIN (all right + matching left), FULL OUTER JOIN (all rows from both).
Card 4
What is a primary key?
A primary key uniquely identifies each record in a table. It must be unique, not null, and each table can have only one primary key.
Card 5
What is a foreign key?
A foreign key is a field that references the primary key of another table, establishing a relationship between tables.
Card 6
What is normalization?
Card 7
What are aggregate functions in SQL?