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Basic Queries of Cloudberry Database

This document introduce the basic queries of Cloudberry Database.

Cloudberry Database is a high-performance, highly parallel data warehouse developed based on PostgreSQL and Greenplum. Here are some examples of the basic query syntax.

  • SELECT: Used to retrieve data from databases & tables.

    SELECT * FROM employees;  -- Queries all data in the employees table.
  • Conditional query (WHERE): Used to filter result sets based on certain conditions.

    SELECT * FROM employees WHERE salary > 50000;  -- Queries employee information with salary exceeding 50,000.
  • ORDER BY: Used to sort query results by one or more columns.

    SELECT * FROM employees ORDER BY salary DESC;  -- Sorts employee information in descending order by salary.
  • Aggregation functions: such as COUNT, SUM, AVG, MAX, MIN, used for calculating statistics from datasets.

    SELECT AVG(salary) FROM employees;  -- Calculates the average salary of employees.
  • GROUP BY: Used in conjunction with aggregation functions to group result sets.

    SELECT department, COUNT(*) FROM employees GROUP BY department;  -- Counts the number of employees by department.
  • Limit the number of results (LIMIT): used to limit the number of rows returned by the query result.

    SELECT * FROM employees LIMIT 10;  -- Only queries the information of the first 10 employees.
  • Join query (JOIN): used to combine data from two or more tables based on related columns.

    FROM employees
    JOIN departments ON employees.department_id =; -- Queries employees and their corresponding department names.
  • Subquery: Nested queries in another SQL query.

    SELECT name FROM employees 
    WHERE department_id IN (SELECT id FROM departments WHERE location = 'New York'); -- Queries all employees working in New York.

The above is just a brief overview of the basic query syntax in Cloudberry Database. Cloudberry Database also provides more advanced queries and functions to help developers perform complex data operations and analyses.

See also