SQL Skills Overview

1. Basic Querying

• SELECT Statements: Writing simple to complex queries to retrieve data from one or more tables.
• JOINs: Combining rows from two or more tables based on a related column between them (INNER, LEFT, RIGHT, and FULL JOINs).
• WHERE Clauses: Filtering records based on specified conditions.

2. Advanced Querying

• Subqueries: Embedding queries within other queries to perform complex operations.
• Common Table Expressions (CTEs): Simplifying complex queries by breaking them into simpler, temporary result sets.
• Window Functions: Performing calculations across a set of table rows related to the current row, using functions like ROW_NUMBER, RANK, and LEAD/LAG.

3. Data Manipulation

• INSERT: Adding new rows of data to a table.
• UPDATE: Modifying existing records in a table.
• DELETE: Removing rows from a table.

4. Data Definition

• CREATE Statements: Defining new tables, views, and other database objects.
• ALTER Statements: Modifying the structure of existing database objects (e.g., adding or dropping columns).
• DROP Statements: Deleting database objects such as tables, views, and indexes.

5. Performance Optimization

• Indexes: Creating and managing indexes to optimize query performance.
• Query Optimization: Techniques to enhance query performance, including indexing strategies, query refactoring, and execution plan analysis.
• Normalization: Structuring databases to reduce redundancy and improve data integrity.

6. Transactions and Concurrency

• Transactions: Grouping a series of operations into a single, atomic unit that can be committed or rolled back.
• ACID Properties: Ensuring database transactions are Atomic, Consistent, Isolated, and Durable.
• Isolation Levels: Understanding and managing the trade-offs between consistency and performance in concurrent transactions.

7. Stored Procedures and Functions

• Stored Procedures: Writing and managing reusable blocks of SQL code that can be executed with parameters.
• User-Defined Functions (UDFs): Creating custom functions for specific operations within SQL queries.
• Triggers: Automatically executing a specified block of code in response to certain events on a table or view.

8. Database Security

• User Management: Creating and managing database users and roles, and assigning permissions.
• Encryption: Implementing encryption for data at rest and in transit.
• SQL Injection Prevention: Writing secure queries to prevent SQL injection attacks.

9. Reporting and Data Analysis

• Aggregations: Using GROUP BY, HAVING, and aggregate functions (SUM, AVG, COUNT, etc.) to summarize data.
• Pivot Tables: Transforming row-level data into a summary format using PIVOT and UNPIVOT operations.
• Views: Creating and managing virtual tables to simplify complex queries and secure data access.

10. Database Administration

• Backup and Restore: Strategies for data backup, disaster recovery, and restoring databases from backups.
• Database Migration: Techniques for moving data between different database systems or versions.
• Monitoring and Maintenance: Regular database health checks, including analyzing logs, checking for fragmentation, and performance tuning.

11. Development and Collaboration Tools

• SQL Server Management Studio (SSMS): A comprehensive tool for managing and developing SQL Server databases.
• pgAdmin: A feature-rich tool for managing PostgreSQL databases.
• Version Control with SQL: Techniques for managing SQL scripts and database changes using version control systems like Git.