SQL tutorial v14
EDB Postgres Advanced Server is a relational database management system (RDBMS). That means it's a system for managing data stored in relations. A relation is essentially a mathematical term for a table. The notion of storing data in tables is so commonplace today that it might seem obvious, but there are a number of other ways of organizing databases. Files and directories on Unix-like operating systems form an example of a hierarchical database. A more modern development is the object-oriented database.
Each table is a named collection of rows. Each row of a given table has the same set of named columns, and each column is of a specific data type. Whereas columns have a fixed order in each row, it's important to remember that SQL doesn't guarantee the order of the rows in the table in any way (although you can explicitly sort them for display).
Tables are grouped into databases, and a collection of databases managed by a single EDB Postgres Advanced Server instance constitutes a database cluster.
sample_database creating_a_new_table populating_a_table_with_rows querying_a_table joins_between_tables aggregate_functions updates deletions the_sql_language