Structured Query Language (SQL)

Overview

• SQL: Standard language for communicating with relational database management systems (RDBMS).
• Databases: Examples include MySQL, PostgreSQL, Microsoft SQL Server, Oracle.
• History: Developed in the early 1970s to interact with IBM's System R database, standardized in 1986.

Relational Databases

• Data Organization: Tables (like Excel spreadsheets).
  • Columns: Attributes or types of data.
  • Rows: Individual records (data points) with a unique ID (primary key).
• Primary Key: Unique identifier for each row.
• Foreign Key: Reference to a primary key in another table.
• Relationships: Example - Teams table (primary key: team ID) and Players table (foreign key: team ID).
  • One player belongs to one team.
  • One team can have many players.

Data Normalization

• Goal: Structure data in its smallest normal form to eliminate duplication and redundancy.

SQL Syntax

• Statements: Code pieces to read or write to the database.
• Key Parts: Keywords for database manipulation.
  • SELECT: Query columns from a table. Column and table names are identifiers.
  • WHERE: Filter results by a condition (predicate).
  • JOIN: Connect data from different tables by matching primary and foreign keys.
• Clauses: Collection of statements that make up a full SQL statement.

Execution

• Supported Databases: Hundreds of databases support SQL.

Conclusion

• This was a brief overview of SQL.
• For a full SQL tutorial, like and subscribe.
• See you in the next video!