SQL

What: SQL (Structured Query Language) is a domain-specific language used in programming and managing relational databases. It allows users to query and manipulate data stored in a relational database management system (RDBMS).

When:

• Use SQL when working with databases to retrieve, update, or manipulate data efficiently.
• SQL is essential for data management tasks such as data cleaning, transformation, and aggregation.
• SQL is widely used in business environments for querying databases, generating reports, and extracting insights from large datasets.

Access: Free! SQL is just a way to query a relational database, which you can think of as a table — just like Excel.

Example: Calculating call lengths and sorting by employee ID and call start time.

  
    -- A list of all calls together with the call duration
    SELECT
      call.*,
      DATEDIFF('SECOND', call.start_time, call.end_time) AS call_duration
    FROM call
    ORDER BY
      call.employee_id ASC,
      call.start_time ASC;