CRUD (create, read, update and delete) - definition & overview

CRUD is an acronym that comes from the world of computer programming and refers to the four functions that are considered necessary to implement a persistent storage application: create, read, update and delete. Persistent storage refers to any data storage device that retains power after the device is powered off, such as a hard disk or a solid-state drive. In contrast, random access memory and internal caching are two examples of volatile memory - they contain data that will be erased when they lose power.

Organizations that keep track of customer data, accounts, payment information, health data, and other records require data storage hardware and applications that provide persistent storage. This data is typically organized into a database, which is simply an organized collection of data that may be viewed electronically. There are many types of databases: hierarchical databases, graph databases, and object-oriented databases to name a few. The most commonly implemented type of database is a relational database, which consists of data tabled in rows and columns and connected to other tables with complementary information by a system of keywords that includes primary keys and foreign keys.

The CRUD acronym identifies all of the major functions that are inherent to relational databases and the applications used to manage them, which include Oracle Database, Microsoft SQL Server, MySQL, and others.

A relational database consists of tables with rows and columns. In a relational database, each row of a table is known as a tuple or a record. Each column of the table represents a specific attribute or field. The four CRUD functions can be called by users to perform different types of operations on selected data within the database. This could be accomplished using code or through a graphical user interface. Let's review each of the four components in-depth to fully appreciate their collective importance in facilitating database interactions.

Create

The create function allows users to create a new record in the database. In the SQL relational database application, the Create function is called INSERT. In Oracle HCM Cloud, it is called create. Remember that a record is a row and that columns are termed attributes. A user can create a new row and populate it with data that corresponds to each attribute, but only an administrator might be able to add new attributes to the table itself.

Read

The read function is similar to a search function. It allows users to search and retrieve specific records in the table and read their values. Users may be able to find desired records using keywords, or by filtering the data based on customized criteria. For example, a database of cars might enable users to type in "1996 Toyota Corolla," or it might provide options to filter search results by make, model and year.

Update

The update function is used to modify existing records that exist in the database. To fully change a record, users may have to modify information in multiple fields. For example, a restaurant that stores recipes for menu items in a database might have a table whose attributes are "dish," "cooking time," "cost" and "price." One day, the chef decides to replace an ingredient in the dish with something different. As a result, the existing record in the database must be changed and all of the attribute values changed to reflect the characteristics of the new dish. In both SQL and Oracle HCM cloud, the update function is simply called "Update."

Delete

The delete function allows users to remove records from a database that is no longer needed. Both SQL and Oracle HCM Cloud have a delete function that allows users to delete one or more records from the database. Some relational database applications may permit users to perform either a hard delete or a soft delete. A hard delete permanently removes records from the database, while a soft delete might simply update the status of a row to indicate that it has been deleted while leaving the data present and intact.

CRUD operations are widely used in many applications that are supported by underlying relational databases. These four basic CRUD functions are incredibly versatile in how they can support a variety of important functions across different business models and industry verticals. Let's look at an example of how CRUD is implemented.

An enterprise organization maintains a human resources department that helps manage to staff and keep track of existing employees. The HR department manages a relational database application with various tables that track different types of employee information:

• An Employees Table includes attributes such as first and last name, employee identification number, contact number, home address, work location, and any other relevant personal details.
• An HR Data Table that includes the employee's payroll information, social security number, employee ID and salary.
• A Locations Table that contains attribute data for each of the company's physical locations, including building ID, address, zip code, the name of the manager, etc.

When a new employee is hired, someone new is added to the payroll, or the company acquires a new location, the HR department creates a record to reflect the changes. If the business needs to send a letter to one or more employees, the read function might be used to find the correct mailing address for the employee. If an employee's salary or contact information changes, the HR department may need to update the existing record to reflect the change.

If an employee leaves the company, the company may choose to perform a soft or hard delete of their information in the database. Here, a soft delete might be appropriate as the organization wishes to retain data on the individual without cluttering up future searches or filtered results.

CRUD testing is a black-box testing technique to validate the functionality of a software product. This term for database testing is applicable for SQL and other databases and ensures proper data mapping, data integrity, maintaining of ACID properties, and accuracy of business rules.

The above example is just one way that CRUD functions enable organizations to achieve their business objectives. CRUD operations are also used to manage forums, eCommerce stores, social media websites and many, many other types of applications that are supported by a relational database.

IT organizations that deploy databases into the cloud gain important capabilities with Sumo Logic that make it easier to monitor the overall health of the deployment, check slow server status, and rapidly identify errors, slow execution times and stopped servers.

Sumo Logic's log aggregation capabilities can be used to monitor the total volume of CRUD commands over time, correlate the results with other important metrics, and help identify and rectify the causes of poor performance.