SQL Fundamentals and Database Design

SQL Syntax

• Basic Syntax:
  • SELECT statements: retrieve data from a database
  • FROM clause: specifies the table(s) to retrieve data from
  • WHERE clause: filters data based on conditions
  • GROUP BY clause: groups data based on one or more columns
  • HAVING clause: filters grouped data based on conditions
• Data Manipulation:
  • INSERT statements: adds new data to a table
  • UPDATE statements: modifies existing data in a table
  • DELETE statements: deletes data from a table
• Data Control:
  • CREATE statements: creates a new database object (e.g., table, index)
  • DROP statements: deletes a database object
  • ALTER statements: modifies a database object

Query Optimization

• Indexing:
  • Creates a data structure to quickly locate data
  • Improves query performance by reducing scan time
• Query Optimization Techniques:
  • Reordering joins: optimizes join operations
  • Subquery optimization: optimizes subqueries
  • Index selection: chooses the best index for a query
• Query Tuning:
  • Analyzes query execution plans
  • Identifies performance bottlenecks
  • Applies optimization techniques

Normalization

• First Normal Form (1NF):
  • Eliminates repeating groups in a table
  • Each row has a unique combination of values
• Second Normal Form (2NF):
  • Each non-key attribute depends on the entire primary key
  • No partial dependencies
• Third Normal Form (3NF):
  • No transitive dependencies
  • Each non-key attribute depends only on the primary key
• Higher Normal Forms:
  • Boyce-Codd Normal Form (BCNF)
  • Fourth Normal Form (4NF)
  • Fifth Normal Form (5NF)
• Denormalization:
  • Intentionally violating normalization rules
  • Improves performance by reducing joins

Test your knowledge of SQL syntax, query optimization, and database normalization. Learn about data manipulation, control, and querying techniques. Improve your skills in database design and optimization.