MODULE 4_JAYBEE D. MARANAN

 WHAT IS SQL?

SQL (Structured Query Language) is a standard language used for storing, manipulating, and retrieving data in databases. It provides a consistent way to interact with various database management systems (DBMS) such as MySQL, SQL Server, Oracle, and more. Here are some key points about SQL:

  1. Data Manipulation:

    • SQL allows you to perform various operations on data:
      • Querying: Retrieving specific data from tables using the SELECT statement.
      • Inserting: Adding new records into tables using the INSERT INTO statement.
      • Updating: Modifying existing records using the UPDATE statement.
      • Deleting: Removing records from tables using the DELETE FROM statement.



  2. Data Definition:

    • SQL includes commands for defining and modifying the structure of database objects:
      • Creating Tables: Using the CREATE TABLE statement.
      • Altering Tables: Modifying existing table structures with ALTER TABLE.
      • Dropping Tables: Deleting tables with DROP TABLE.
      • Creating Indexes: Improving data retrieval performance with CREATE INDEX.
      • Creating Views: Defining virtual tables with CREATE VIEW.

  3. Querying Data:

    • The primary SQL statement for retrieving data is the SELECT statement.
    • Example:
      SQL
      SELECT column1, column2 FROM my_table WHERE condition;
      AI-generated code. Review and use carefully. More info on FAQ.
      • Replace column1, column2, and my_table with actual column names and table names.

  4. Database Independence:

    • SQL provides a consistent interface regardless of the specific DBMS being used.
    • Developers can write SQL queries that work across different database systems.

  5. SQL Variants:

    • Different DBMSs have their own SQL dialects (e.g., MySQL, SQL Server, PostgreSQL).
    • While the core SQL syntax remains similar, there are variations in features and functions.

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