From Simple English Wikipedia, the free encyclopedia
A database (DB), in the most general sense, is an organized collection of data. More specifically, a database is an electronic system that allows data to be easily accessed, manipulated and updated. In other words, a database is used by an organization as a method of. Azure SQL Database is the right solution for cloud-designed applications when developer productivity and fast time-to-market for new solutions are critical. With programmatic DBA-like functionality, it is perfect for cloud architects and developers as it lowers the need for managing the underlying operating system and database. Oracle Database (commonly referred to as Oracle DBMS or simply as Oracle) is a multi-model database management system produced and marketed by Oracle Corporation. It is a database commonly used for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database workloads. Oracle Database is available by serveral service providers on-prem, on-cloud, or as.
A database is a system for storing and taking care of data (any kind of information).
A database engine can sort, change or serve the information on the database. The information itself can be stored in many different ways; before digital computers, card files, printed books and other methods were used. Now most data is kept on computer files.
Computer Database
A database system is a computer program for managing electronic databases. A very simple example of a database system would be an electronic address book.
The data in a database is organized in some way. Before there were computers, employee data was often kept in filing cabinets. There was usually one card for each employee. On the card, information such as the date of birth or the name of the employee could be found. A database also has such 'cards'. To the user, the card will look the same as it did in old times, only this time it will be on the screen. To the computer, the information on the card can be stored in different ways. Each of these ways is known as a database model. The most commonly used database model is called the relational database model. It uses relations and sets to store the data. Normal users talking about the database model will not talk about relations; instead, they will talk about database tables.
Uses for database systems[change | change source]
Uses for database systems include:
- They store data and provide facilities (tools) to search for specific records in a given set of data.
- They store special information used to manage the data. This information is called metadata and it is not shown to all the people looking at the data.
- They can solve cases where many users want to access (and possibly change) the same entries of data.
- They manage access rights (who is allowed to see the data, who can change it)
- When there are many users asking questions to the database, the questions must be answered faster. In this way, the last person to ask a question can get an answer in a reasonable time.
- Certain attributes are more important than others and can be used to find other data. This is called indexing. An index contains all the important data and can be used to find other data.
- They ensure that the data always has context. There are a lot of different rules that can be added to tell the database system if the data makes sense. One of the rules might say November has 30 days. This means if someone wants to enter November 31 as a date, this change will be rejected.
Changing data[change | change source]
In databases, some data changes occasionally. There may be problems when data is changed; for example, an error might have occurred. The error might make the data useless. The database system looks at the data to ensure that it meets certain requirements. It does this by using a transaction. There are two points in time in the database, the time before the data was changed, and the time after the data was changed. If something goes wrong when changing the data, the database system simply puts the database back into the state before the change happened. This is called a rollback. After all the changes are done successfully, they are committed. This means that the data makes sense again; committed changes can no longer be undone.
In order to be able to do this, databases follow the ACID principle: Drifting lands 1 0.
- All. Either all tasks of a given set (called a transaction) are done, or none of them is. This is known as Atomicity.
- Complete. The data in the database always makes sense. There is no half-done (invalid) data. This is known as Consistency.
- Independent. If many people work on the same data, they will not see (or impact) each other. Each of them has their own view of the database, which is independent of the others. This is known as Isolation.
- Done. Transactions must be committed, when they are done. Once the committed, they can not be undone. This is known as Durability.
Database model[change | change source]
Synergy 1 8 8. There are different ways how to represent the data.
- Simple files (called flat files): This is the most simple form of Database system. All the data is stored in a file in plain text. Every piece of information can be separated by a new line or a comma etc.
- Hierarchical model: The data is organized like a tree structure. The interesting data is at the leaves of the tree. The relationships among the data entries is such that some entries are directly dependent to other entries.
- Network model: Use records and sets to store the data. Similar to Hierarchical model, but this has much more complex structure.
- Relational model: This uses set theory and predicate logic. It is widely used. Data looks like it is organized in tables. These tables can then be joined together so that simple queries can be chosen from them.
- Object oriented model: The data is represented in the form of objects as used in Object Oriented Programming. They can interact directly with the OOP language being used, as both of them have the same representation of the data internally.
- Object relational model: This is a hybrid of the Object oriented model and the relational model.
- NoSQL model: This is a new kind of database model and is increasing being used in the industry in big data and real-time web applications.[1] The data in this model is stored as key-value pairs without any strict hierarchy as in other models. NoSQL systems are also referred to as 'Not only SQL' because they do not allow Structured Query Language-like query languages to be used.
Ways to organize the data[change | change source]
As in real life, the same data can be looked at from different perspectives, and it can be organized in different ways. There are different things to consider, when organizing the data:
- Each item of data should be stored as few times as possible. Imagine that an unmarried woman is listed in the county records, State Motor Vehicle Department, Federal Social Security Department and International Passport Department. If she marries, and decides to change her name, all the these departments have to be notified. If all the departments were linked, and her name stored in only one place, then updating is easy.
- If the data is stored in several different databases, it may contradict itself.
- This problem makes finding data slower. If there is a lot of data, this problem of storing one piece of data in many places, will take up a lot of space. In our example there were four databases for one person. That will be eight changes made, if a second person has exactly the same problem.
- If you have this problem, a method called Database Normalisation was developed to solve it. Currently there are six Normal forms. These are ways to make a database faster, and make the data take less space.
References[change | change source]
- ↑'RDBMS dominate the database market, but NoSQL systems are catching up'. DB-Engines.com. 21 Nov 2013. Retrieved 24 Nov 2013.
Related pages[change | change source]
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Azure SQL is a family of managed, secure, and intelligent products that use the SQL Server database engine in the Azure cloud.
- Azure SQL Database: Support modern cloud applications on an intelligent, managed database service, that includes serverless compute.
- Azure SQL Managed Instance: Modernize your existing SQL Server applications at scale with an intelligent fully managed instance as a service, with almost 100% feature parity with the SQL Server database engine. Best for most migrations to the cloud.
- SQL Server on Azure VMs: Lift-and-shift your SQL Server workloads with ease and maintain 100% SQL Server compatibility and operating system-level access.
![Database Is Database Is](https://image3.slideserve.com/6968707/what-is-a-database-n.jpg)
Azure SQL is built upon the familiar SQL Server engine, so you can migrate applications with ease and continue to use the tools, languages, and resources you're familiar with. Your skills and experience transfer to the cloud, so you can do even more with what you already have.
Learn how each product fits into Microsoft's Azure SQL data platform to match the right option for your business requirements. Whether you prioritize cost savings or minimal administration, this article can help you decide which approach delivers against the business requirements you care about most.
If you're new to Azure SQL, check out the What is Azure SQL video from our in-depth Azure SQL video series:
Overview
In today'ss data platform leverages SQL Server technology and makes it available across physical on-premises machines, private cloud environments, third-party hosted private cloud environments, and the public cloud.
Fully managed and always up to date
Spend more time innovating and less time patching, updating, and backing up your databases. Azure is the only cloud with evergreen SQL that automatically applies the latest updates and patches so that your databases are always up to date—eliminating end-of-support hassle. Even complex tasks like performance tuning, high availability, disaster recovery, and backups are automated, freeing you to focus on applications.
Protect your data with built-in intelligent security
Azure constantly monitors your data for threats. With Azure SQL, you can:
- Remediate potential threats in real time with intelligent advanced threat detection and proactive vulnerability assessment alerts.
- Get industry-leading, multi-layered protection with built-in security controls including T-SQL, authentication, networking, and key management.
- Take advantage of the most comprehensive compliance coverage of any cloud database service.
Business motivations
There are several factors that can influence your decision to choose between the different data offerings:
- Cost: Both PaaS and IaaS option include base price that covers underlying infrastructure and licensing. However, with IaaS option you need to invest additional time and resources to manage your database, while in PaaS you get these administration features included in the price. IaaS enables you to shut down resources while you are not using them to decrease the cost, while PaaS is always running unless you drop and re-create your resources when they are needed.
- Administration: PaaS options reduce the amount of time that you need to invest to administer the database. However, it also limits the range of custom administration tasks and scripts that you can perform or run. For example, the CLR is not supported with SQL Database, but is supported for an instance of SQL Managed Instance. Also, no deployment options in PaaS support the use of trace flags.
- Service-level agreement: Both IaaS and PaaS provide high, industry standard SLA. PaaS option guarantees 99.99% SLA, while IaaS guarantees 99.95% SLA for infrastructure, meaning that you need to implement additional mechanisms to ensure availability of your databases. You can attain 99.99% SLA by creating an additional SQL virtual machine, and implementing the SQL Server Always On availability group high availability solution.
- Time to move to Azure: SQL Server on Azure VM is the exact match of your environment, so migration from on-premises to the Azure VM is no different than moving the databases from one on-premises server to another. SQL Managed Instance also enables easy migration; however, there might be some changes that you need to apply before your migration.
Service comparison
What Is Database Security
As seen in the diagram, each service offering can be characterized by the level of administration you have over the infrastructure, and by the degree of cost efficiency.
In Azure, you can have your SQL Server workloads running as a hosted service (PaaS), or a hosted infrastructure (IaaS). Within PaaS, you have multiple product options, and service tiers within each option. The key question that you need to ask when deciding between PaaS or IaaS is do you want to manage your database, apply patches, and take backups, or do you want to delegate these operations to Azure?
Azure SQL Database
Azure SQL Database is a relational database-as-a-service (DBaaS) hosted in Azure that falls into the industry category of Platform-as-a-Service (PaaS).
- Best for modern cloud applications that want to use the latest stable SQL Server features and have time constraints in development and marketing.
- A fully managed SQL Server database engine, based on the latest stable Enterprise Edition of SQL Server. SQL Database has two deployment options built on standardized hardware and software that is owned, hosted, and maintained by Microsoft.
With SQL Server, you can use built-in features and functionality that requires extensive configuration (either on-premises or in an Azure virtual machine). When using SQL Database, you pay-as-you-go with options to scale up or out for greater power with no interruption. SQL Database has some additional features that are not available in SQL Server, such as built-in high availability, intelligence, and management.
Azure SQL Database offers the following deployment options:
- As a single database with its own set of resources managed via a logical SQL server. A single database is similar to a contained database in SQL Server. This option is optimized for modern application development of new cloud-born applications. Hyperscale and serverless options are available.
- An elastic pool, which is a collection of databases with a shared set of resources managed via a logical SQL server. Single databases can be moved into and out of an elastic pool. This option is optimized for modern application development of new cloud-born applications using the multi-tenant SaaS application pattern. Elastic pools provide a cost-effective solution for managing the performance of multiple databases that have variable usage patterns.
Azure SQL Managed Instance
Azure SQL Managed Instance falls into the industry category of Platform-as-a-Service (PaaS), and is best for most migrations to the cloud. SQL Managed Instance is a collection of system and user databases with a shared set of resources that is lift-and-shift ready.
- Best for new applications or existing on-premises applications that want to use the latest stable SQL Server features and that are migrated to the cloud with minimal changes. An instance of SQL Managed Instance is similar to an instance of the Microsoft SQL Server database engine offering shared resources for databases and additional instance-scoped features.
- SQL Managed Instance supports database migration from on-premises with minimal to no database change. This option provides all of the PaaS benefits of Azure SQL Database but adds capabilities that were previously only available in SQL Server VMs. This includes a native virtual network and near 100% compatibility with on-premises SQL Server. Instances of SQL Managed Instance provide full SQL Server access and feature compatibility for migrating SQL Servers to Azure.
SQL Server on Azure VM
SQL Server on Azure VM falls into the industry category Infrastructure-as-a-Service (IaaS) and allows you to run SQL Server inside a fully managed virtual machine (VM) in Azure.
- Best for migrations and applications requiring OS-level access. SQL virtual machines in Azure are lift-and-shift ready for existing applications that require fast migration to the cloud with minimal changes or no changes. SQL virtual machines offer full administrative control over the SQL Server instance and underlying OS for migration to Azure.
- Rapid development and test scenarios when you do not want to buy on-premises non-production SQL Server hardware. SQL virtual machines also run on standardized hardware that is owned, hosted, and maintained by Microsoft. When using SQL virtual machines, you can either pay-as-you-go for a SQL Server license already included in a SQL Server image or easily use an existing license. You can also stop or resume the VM as needed.
- SQL Server installed and hosted in the cloud runs on Windows Server or Linux virtual machines running on Azure, also known as an infrastructure as a service (IaaS). SQL virtual machines are a good option for migrating on-premises SQL Server databases and applications without any database change. All recent versions and editions of SQL Server are available for installation in an IaaS virtual machine.The most significant difference from SQL Database and SQL Managed Instance is that SQL Server on Azure Virtual Machines allows full control over the database engine. You can choose when to start maintenance/patching, change the recovery model to simple or bulk-logged, pause or start the service when needed, and you can fully customize the SQL Server database engine. With this additional control comes the added responsibility to manage the virtual machine.
- Optimized for migrating existing applications to Azure or extending existing on-premises applications to the cloud in hybrid deployments. In addition, you can use SQL Server in a virtual machine to develop and test traditional SQL Server applications. With SQL virtual machines, you have the full administrative rights over a dedicated SQL Server instance and a cloud-based VM. It is a perfect choice when an organization already has IT resources available to maintain the virtual machines. These capabilities allow you to build a highly customized system to address your application’s specific performance and availability requirements.
Additional differences are listed in the following table, but both SQL Database and SQL Managed Instance are optimized to reduce overall management costs to the minimum for provisioning and managing many databases. Ongoing administration costs are reduced since you do not have to manage any virtual machines, operating system, or database software. You do not have to manage upgrades, high availability, or backups.
In general, SQL Database and SQL Managed Instance can dramatically increase the number of databases managed by a single IT or development resource. Elastic pools also support SaaS multi-tenant application architectures with features including tenant isolation and the ability to scale to reduce costs by sharing resources across databases. SQL Managed Instance provides support for instance-scoped features enabling easy migration of existing applications, as well as sharing resources among databases.
Comparison table
Azure SQL Database | Azure SQL Managed Instance | SQL Server on Azure VM |
---|---|---|
Supports most on-premises database-level capabilities. The most commonly used SQL Server features are available. 99.995% availability guaranteed. Built-in backups, patching, recovery. Latest stable Database Engine version. Ability to assign necessary resources (CPU/storage) to individual databases. Built-in advanced intelligence and security. Online change of resources (CPU/storage). | Supports almost all on-premises instance-level and database-level capabilities. High compatibility with SQL Server. 99.99% availability guaranteed. Built-in backups, patching, recovery. Latest stable Database Engine version. Easy migration from SQL Server. Private IP address within Azure Virtual Network. Built-in advanced intelligence and security. Online change of resources (CPU/storage). | You have full control over the SQL Server engine. Supports all on-premises capabilities. Up to 99.99% availability. Full parity with the matching version of on-premises SQL Server. Fixed, well-known Database Engine version. Easy migration from SQL Server. Private IP address within Azure Virtual Network. You have the ability to deploy application or services on the host where SQL Server is placed. |
Migration from SQL Server might be challenging. Some SQL Server features are not available. No guaranteed exact maintenance time (but nearly transparent). Compatibility with the SQL Server version can be achieved only using database compatibility levels. Private IP address support with Azure Private Link. | There is still some minimal number of SQL Server features that are not available. No guaranteed exact maintenance time (but nearly transparent). Compatibility with the SQL Server version can be achieved only using database compatibility levels. | You need to manage your backups and patches. You need to implement your own High-Availability solution. There is a downtime while changing the resources(CPU/storage) |
Databases of up to 100 TB. | Up to 8 TB. | SQL Server instances with up to 256 TB of storage. The instance can support as many databases as needed. |
On-premises application can access data in Azure SQL Database. | Native virtual network implementation and connectivity to your on-premises environment using Azure Express Route or VPN Gateway. | With SQL virtual machines, you can have applications that run partly in the cloud and partly on-premises. For example, you can extend your on-premises network and Active Directory Domain to the cloud via Azure Virtual Network. For more information on hybrid cloud solutions, see Extending on-premises data solutions to the cloud. |
Cost
Whether you're a startup that is strapped for cash, or a team in an established company that operates under tight budget constraints, limited funding is often the primary driver when deciding how to host your databases. In this section, you learn about the billing and licensing basics in Azure associated with the Azure SQL family of services. You also learn about calculating the total application cost.
Billing and licensing basics
Currently, both SQL Database and SQL Managed Instance are sold as a service and are available with several options and in several service tiers with different prices for resources, all of which are billed hourly at a fixed rate based on the service tier and compute size you choose. For the latest information on the current supported service tiers, compute sizes, and storage amounts, see DTU-based purchasing model for SQL Database and vCore-based purchasing model for both SQL Database and SQL Managed Instance.
- With SQL Database, you can choose a service tier that fits your needs from a wide range of prices starting from 5$/month for basic tier and you can create elastic pools to share resources among databases to reduce costs and accommodate usage spikes.
- With SQL Managed Instance, you can also bring your own license. For more information on bring-your-own licensing, see License Mobility through Software Assurance on Azure or use the Azure Hybrid Benefit calculator to see how to save up to 40%.
In addition, you are billed for outgoing Internet traffic at regular data transfer rates. You can dynamically adjust service tiers and compute sizes to match your application’s varied throughput needs.
With SQL Database and SQL Managed Instance, the database software is automatically configured, patched, and upgraded by Azure, which reduces your administration costs. In addition, its built-in backup capabilities help you achieve significant cost savings, especially when you have a large number of databases.
With SQL on Azure VMs, you can use any of the platform-provided SQL Server images (which includes a license) or bring your SQL Server license. All the supported SQL Server versions (2008R2, 2012, 2014, 2016, 2017, 2019) and editions (Developer, Express, Web, Standard, Enterprise) are available. In addition, Bring-Your-Own-License versions (BYOL) of the images are available. When using the Azure provided images, the operational cost depends on the VM size and the edition of SQL Server you choose. Regardless of VM size or SQL Server edition, you pay per-minute licensing cost of SQL Server and the Windows or Linux Server, along with the Azure Storage cost for the VM disks. The per-minute billing option allows you to use SQL Server for as long as you need without buying addition SQL Server licenses. If you bring your own SQL Server license to Azure, you are charged for server and storage costs only. For more information on bring-your-own licensing, see License Mobility through Software Assurance on Azure. In addition, you are billed for outgoing Internet traffic at regular data transfer rates.
Calculating the total application cost
When you start using a cloud platform, the cost of running your application includes the cost for new development and ongoing administration costs, plus the public cloud platform service costs.
For more information on pricing, see the following resources:
- Virtual machine pricing for SQL and for Windows
Administration
For many businesses, the decision to transition to a cloud service is as much about offloading complexity of administration as it is cost. With IaaS and PaaS, Azure administers the underlying infrastructure and automatically replicates all data to provide disaster recovery, configures and upgrades the database software, manages load balancing, and does transparent failover if there is a server failure within a data center.
- With SQL Database and SQL Managed Instance, you can continue to administer your database, but you no longer need to manage the database engine, the operating system, or the hardware. Examples of items you can continue to administer include databases and logins, index and query tuning, and auditing and security. Additionally, configuring high availability to another data center requires minimal configuration and administration.
- With SQL on Azure VM, you have full control over the operating system and SQL Server instance configuration. With a VM, it's up to you to decide when to update/upgrade the operating system and database software and when to install any additional software such as anti-virus. Some automated features are provided to dramatically simplify patching, backup, and high availability. In addition, you can control the size of the VM, the number of disks, and their storage configurations. Azure allows you to change the size of a VM as needed. For information, see Virtual Machine and Cloud Service Sizes for Azure.
Service-level agreement (SLA)
For many IT departments, meeting up-time obligations of a service-level agreement (SLA) is a top priority. In this section, we look at what SLA applies to each database hosting option.
For both Azure SQL Database and Azure SQL Managed Instance, Microsoft provides an availability SLA of 99.99%. For the latest information, see Service-level agreement.
For SQL on Azure VM, Microsoft provides an availability SLA of 99.95% that covers just the virtual machine. This SLA does not cover the processes (such as SQL Server) running on the VM and requires that you host at least two VM instances in an availability set. For the latest information, see the VM SLA. For database high availability (HA) within VMs, you should configure one of the supported high availability options in SQL Server, such as Always On availability groups. Using a supported high availability option doesn't provide an additional SLA, but allows you to achieve >99.99% database availability.
Time to move to Azure
Azure SQL Database is the right solution for cloud-designed applications when developer productivity and fast time-to-market for new solutions are critical. With programmatic DBA-like functionality, it is perfect for cloud architects and developers as it lowers the need for managing the underlying operating system and database.
Azure SQL Managed Instance greatly simplifies the migration of existing applications to Azure, enabling you to bring migrated database applications to market in Azure quickly.
SQL on Azure VM is perfect if your existing or new applications require large databases or access to all features in SQL Server or Windows/Linux, and you want to avoid the time and expense of acquiring new on-premises hardware. It is also a good fit when you want to migrate existing on-premises applications and databases to Azure as-is - in cases where SQL Database or SQL Managed Instance is not a good fit. Since you do not need to change the presentation, application, and data layers, you save time and budget on re-architecting your existing solution. Instead, you can focus on migrating all your solutions to Azure and in doing some performance optimizations that may be required by the Azure platform. For more information, see Performance Best Practices for SQL Server on Azure Virtual Machines.
Create and manage Azure SQL resources with the Azure portal
The Azure portal provides a single page where you can manage all of your Azure SQL resources including your SQL virtual machines.
To access the Azure SQL page, from the Azure portal menu, select Azure SQL or search for and select Azure SQL in any page.
Note
Azure SQL provides a quick and easy way to access all of your SQL resources in the Azure portal, including single and pooled database in Azure SQL Database as well as the logical SQL server hosting them, SQL Managed Instances, and SQL virtual machines. Azure SQL is not a service or resource, but rather a family of SQL-related services.
To manage existing resources, select the desired item in the list. To create new Azure SQL resources, select + Add.
After selecting + Add, view additional information about the different options by selecting Show details on any tile.
For details, see:
Next steps
- See Your first Azure SQL Database to get started with SQL Database.
- See Your first Azure SQL Managed Instance to get started with SQL Managed Instance.
- See SQL Database pricing.
- See Provision a SQL Server virtual machine in Azure to get started with SQL Server on Azure VMs.
- Identify the right SQL Database or SQL Managed Instance SKU for your on-premises database.