Learn to write SQL from your first SELECT to joins, window functions and interview queries, and understand indexes, transactions and isolation. For beginners and developers preparing for SQL and backend interviews.
A database that stores data in tables of rows and columns
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Each table holds one kind of thing, such as customers or orders, and tables refer to each other through shared key values. "Relation" is the mathematician's word for a table, which is where the name comes from. PostgreSQL, MySQL, SQLite, SQL Server and Oracle are all relational databases.
