Azure SQL Database is a fully managed platform as a service (PaaS) database engine that handles most of the database management functions such as upgrading, patching, backups, and monitoring without user involvement.Azure SQL Database is always running on the latest stable version of the SQL Server database engine and patched OS with 99.99% availability. PaaS capabilities that are built into Azure SQL Database enable you to focus on the domain-specific database administration and optimization activities that are critical for your business.

Azure Cosmos DB is a fully managed NoSQL database service for modern app development. Get guaranteed single-digit millisecond response times and 99.999-percent availability, backed by SLAs, automatic and instant scalability, and open-source APIs for MongoDB and Cassandra.

Has a vCore-based purchase model, for those who look for flexibility, control and transparency of individual resource consumption.

$0.5218 vCore-hour rate.

$0.12 per GB-monthly in Locally Redundant Storage.

Backup storage and long term retention have varying prices.

Example Price

10 vCores ($5,218) with 10GB of storage ($1,2) alongside 10GB of LRS storage and retention ($1+$0,25) $7,668 USD

Example Pricing

10M Serverless Request Units ($2,82), 10GB of consumed storage ($2,5), 10 GB of backup storage ($1,5) $6,82USD 

Onboarding
Massive documentation, free to start. Might be a bit overwhelming at first.

​Scalability
Configurable autoscaling.

Regions

Azure SQL Database is available on all the platforms that have Azure available, such as the United States, Europe, Asia Pacific, and more to come.

​Backups 
With Azure SQL Database, you can set a long-term backup retention policy (LTR) to automatically retain backups in separate Azure Blob storage containers for up to 10 years. You can then recover a database using these backups using the Azure portal or PowerShell.

​Security
​Supports JWT, ABAC-based role, and permissions. Identity and anonymous-base

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​Onboarding
Great documentation to start things off.

​Scalability

Includes the ability to autoscale, with configuration options for it.

Regions

Azure Cosmos DB is available on all the platforms that have Azure available, such as the United States, Europe, Asia Pacific, and more to come.

​Backups 

Azure Cosmos DB automatically takes backups of your data at regular intervals. The automatic backups are taken without affecting the performance or availability of the database operations. Azure Cosmos DB automatically takes a full backup of your database every 4 hours and at any point of time, only the latest two backups are stored by default. If the default intervals aren't sufficient for your workloads, you can change the backup interval and the retention period from the Azure portal.

​Security
If you choose an on-premises solution, you need to provide everything from end-point protection to physical security of your hardware - which is no easy task. If you choose a PaaS cloud database provider such as Azure Cosmos DB, your area of concern shrinks considerably.

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With Azure SQL Database, you can create a highly available and high-performance data storage layer for the applications and solutions in Azure. SQL Database can be the right choice for a variety of modern cloud applications because it enables you to process both relational data and non-relational structures, such as graphs, JSON, spatial, and XML.

• ​Fully managed SQL database automates updates, provisioning, and backups so you can focus on application development
  
• Flexible and responsive serverless compute and Hyperscale storage rapidly adapt to your changing requirements
  
• Layers of protection, built-in controls, and intelligent threat detection keep your data secure
  
• Built-in AI and built-in high availability maintain peak performance and durability with an SLA of up to 99.995 percent
  

Azure Cosmos DB is a fully managed NoSQL database for modern app development. Single-digit millisecond response times, and automatic and instant scalability, guarantee speed at any scale.

• ​Guaranteed speed at any scale
  
• Fast, flexible app development with SDKs for popular languages, a native Core (SQL) API along with APIs for MongoDB, Cassandra, and Gremlin, and no-ETL (extract, transform, load) analytics
  
• Ready for mission-critical applications
  
• Fully managed and cost-effective serverless database
  
• Serverless database operations
  
• Hybrid platform for Cassandra data
• No-ETL analytics over real-time operational data