MSDN Documentation

Rich Data Type Support

SQL Server offers a comprehensive set of data types to store various kinds of information efficiently. This includes standard numeric, character, and date/time types, as well as advanced types like spatial data, XML, JSON, and hierarchical data.

• INT, BIGINT, DECIMAL, FLOAT
• VARCHAR, NVARCHAR, TEXT
• DATE, TIME, DATETIME2
• XML, JSON
• GEOMETRY, GEOGRAPHY

Proper data type selection is crucial for data integrity, storage efficiency, and query performance.

Transact-SQL (T-SQL)

SQL Server's dialect of SQL, Transact-SQL (T-SQL), is a powerful procedural language extension that allows for complex logic within the database. It supports standard SQL commands alongside procedural constructs.

SELECT TOP 10
    ProductName,
    UnitPrice
FROM
    Products
WHERE
    Discontinued = 0
ORDER BY
    UnitPrice DESC;
                

T-SQL includes constructs for control flow (IF, WHILE), error handling (TRY...CATCH), and variable management.

Stored Procedures

Stored procedures are precompiled sets of one or more T-SQL statements stored in the database. They offer benefits such as:

• Performance: Compiled once and reused, reducing network traffic.
• Security: Granular control over execution permissions.
• Modularity: Encapsulates business logic.
• Maintainability: Simplifies updates to logic.

CREATE PROCEDURE usp_GetProductDetails (@ProductID INT)
AS
BEGIN
    SELECT
        ProductID,
        ProductName,
        ListPrice
    FROM
        Production.Product
    WHERE
        ProductID = @ProductID;
END;
GO

EXEC usp_GetProductDetails @ProductID = 771;
                

Triggers

Triggers are special types of stored procedures that automatically execute in response to certain events on a table or view, such as INSERT, UPDATE, or DELETE operations.

• Data Auditing: Track changes to sensitive data.
• Enforcing Business Rules: Ensure data integrity beyond simple constraints.
• Cascading Actions: Perform related operations on other tables.

Triggers can be defined as AFTER or INSTEAD OF the triggering event.

Indexing Strategies

SQL Server's indexing capabilities are vital for query performance. Different types of indexes help speed up data retrieval:

• Clustered Indexes: Determine the physical storage order of data rows. A table can have only one.
• Non-Clustered Indexes: Provide a logical ordering of data rows but do not affect the physical order. A table can have multiple.
• Columnstore Indexes: Optimized for data warehousing workloads, offering significant compression and query performance for large fact tables.
• Full-Text Indexes: Enable sophisticated text searching capabilities.

Proper index design and maintenance are critical for database performance.

Transactions and Concurrency Control

SQL Server provides robust support for ACID (Atomicity, Consistency, Isolation, Durability) transactions, ensuring data integrity during concurrent operations. Features include:

• Transaction Isolation Levels: Control how transactions are isolated from each other (e.g., READ COMMITTED, REPEATABLE READ, SERIALIZABLE).
• Locking: Mechanisms to prevent conflicting data modifications.
• Deadlock Detection and Resolution: Automatic handling of situations where transactions are blocked indefinitely.
• Optimistic Concurrency: Using row versioning to minimize locking.

Comprehensive Security Features

Protecting sensitive data is paramount. SQL Server offers a multi-layered security approach:

• Authentication: Windows Authentication and SQL Server Authentication.
• Authorization: Role-based security, granular permissions at schema, table, and column levels.
• Encryption: Transparent Data Encryption (TDE), Always Encrypted, Column-level encryption.
• Auditing: SQL Server Audit and Extended Events for tracking database activities.
• Row-Level Security: Enforce access policies directly within the database based on user context.

Replication

Replication enables data distribution across multiple databases and devices. Key types include:

• Snapshot Replication: Copies the entire dataset at a specific point in time.
• Transactional Replication: Replicates individual transactions as they occur.
• Merge Replication: Allows data to be modified at multiple locations and then synchronized, resolving conflicts.

Replication is useful for high availability, disaster recovery, and distributing data to edge locations.

Reliable Backup and Restore

SQL Server provides sophisticated tools and options for backing up and restoring databases, crucial for disaster recovery and point-in-time recovery.

• Recovery Models: Simple, Full, and Bulk-Logged models dictate transaction log behavior and recovery capabilities.
• Backup Types: Full, Differential, and Transaction Log backups.
• Point-in-Time Restore: Recover a database to a specific moment.
• Database Snapshots: Create read-only, static views of a database.

Advanced Performance Tuning Tools

SQL Server includes a suite of tools and features designed to help administrators and developers optimize database performance:

• Query Store: Tracks query performance history, identifies regressions, and allows query plan forcing.
• Dynamic Management Views (DMVs): Provide real-time information about server status and performance.
• Execution Plans: Visualize how the query optimizer executes queries.
• Performance Dashboard Reports: Built-in reports for monitoring performance.

Seamless Cloud Integration

SQL Server integrates deeply with cloud platforms, primarily Azure. Key offerings include:

• Azure SQL Database: A fully managed Platform-as-a-Service (PaaS) offering.
• Azure SQL Managed Instance: Near 100% compatibility with on-premises SQL Server.
• SQL Server on Azure VMs: Deploy SQL Server in virtual machines for maximum control.
• Azure Arc-enabled data services: Extend Azure data services to any infrastructure.

This allows for hybrid cloud strategies and leveraging cloud scalability and manageability.