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What are Integrity Constraints in DBMS? With Examples

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03rd May, 2024
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    What are Integrity Constraints in DBMS? With Examples

    Database systems are integral to the operation of most businesses. A well-designed database system can improve productivity, accuracy, and security. One key aspect of designing a database is understanding integrity constraints.

    This article will explain different integrity constraints and the importance of their role in database design. We'll also look at some common types of integrity constraints in DBMS. Understanding these concepts is essential for creating robust, efficient databases. We will also provide examples of how these constraints can be used to protect your data. If you're eager to delve deeper into this topic, consider enrolling in a Database course where you can explore concepts like entity integrity, referential integrity, domain integrity, and more

    What are Integrity Constraints in DBMS?

    Integrity constraints are rules that help to maintain the accuracy and consistency of data in a database. They can be used to enforce business rules or to ensure that data is entered correctly. For example, a simple integrity constraint in DBMS might state that all customers must have a valid email address. This would prevent someone from accidentally entering an invalid email address into the database. Integrity constraints can also be used to enforce relationships between tables.

    For example, if a customer can only have one shipping address, then an integrity constraint can be used to ensure that only one shipping address is entered for each customer. Enforcing integrity constraints in SQL can help prevent data inconsistencies and errors, making it easier to manage and query the data.

    What is the Purpose of Integrity Constraints?

    Integrity constraints are an important part of maintaining database correctness. They ensure that the data in the database adheres to a set of rules, which can help prevent errors and inconsistencies. In some cases, integrity constraints can be used to enforce business rules, such as ensuring that a customer's balance remains within a certain limit.

    In other cases, they can be used to enforce data integrity, such as ensuring that all values in a column are unique. Integrity constraints in SQL can be either enforced by the database system or by application code. Enforcing them at the database level can help ensure that the rules are always followed, even if the application code is changed. However, enforcing them at the application level can give the developer more flexibility in how the rules are enforced.

    Getting a practical approach to understanding the purpose of integrity constraints needs some professional assistance, so look for the MongoDB Professional certification courses. Their experts will make sure to get hands-on learning along with a grasp of technical knowledge in the easiest way possible.

    Types of Integrity Constraints

    Integrity constraints in DBMS are used to ensure that data is consistent and accurate. There are four main types of integrity constraints: domain, entity, referential, and key. Here, we'll take a closer look & explain the types of integrity constraints along with some examples.

    1. Domain Constraint

    A domain constraint is a restriction on the values that can be stored in a column. For example, if you have a column for "age," domain integrity constraints in DBMS would ensure that only values between 1 and 120 can be entered into that column. This ensures that only valid data is entered into the database.

    Example:

    Consider a Student's table having Roll No, Name, Age, Class of students.

    Roll NoNameAgeClass
    101Adam146
    102Steve168
    103David84
    104Bruce1812
    105Tim6A

    2. Entity Integrity Constraint

    An entity integrity constraint is a restriction on null values. Null values are values that are unknown or not applicable, and they can be problematic because they can lead to inaccurate results. Entity integrity constraints would ensure that null values are not entered into any required columns. For example, if you have a column for "first name," an entity integrity constraint in DBMS would ensure that this column cannot contain any null values.

    Example:

    Consider Employees table having Id, Name, and salary of employees

    IDNameSalary
    1101Jackson40000
    1102Harry60000
    1103Steve80000
    1104Ash1800000

    James36000

    3. Referential Integrity Constraint

    A referential integrity constraint is a restriction on how foreign keys can be used. A foreign key is a column in one table that references a primary key in another table. For example, let's say you have a table of employees and a table of department managers. The "employee ID" column in the employee's table would be a foreign key that references the "manager ID" column in the manager's table.

    Referential integrity constraints in DBMS would ensure that every manager ID in the manager's table has at least one corresponding employee ID in the employee's table. In other words, it would prevent you from assigning an employee to a manager who doesn't exist.

    Example:

    Consider an Employee and a Department table where Dept_ID acts as a foreign key between the two tables

    Employees Table

    IDNameSalaryDept_ID
    1101Jackson400003
    1102Harry600002
    1103Steve800004
    1104Ash18000003
    1105James360001

    Department Table

    Dept_ID
    Dept_Name
    1Sales
    2HR
    3Technical

    4. Key Constraint

    Key constraints in DBMS are a restriction on duplicate values. A key is composed of one or more columns whose values uniquely identify each row in the table. For example, let's say you have a table of products with columns for "product ID" and "product name." The combination of these two values would be the key for each product, and a key constraint would ensure that no two products have the same combination of product ID and product name.

    Example:

    Consider a student's table

    Roll NoNameAgeClass
    101Adam146
    102Steve168
    103David84
    104Bruce1812
    102Tim62

    Types of Key Constraints
    types of the key constraint

    Within databases, a key constraint is a rule that defines how data in a column(s) can be stored in a table. There are several different types of key constraints in DBMS, each with its own specific purpose. Now, we'll take a high-level look at the five most common types of key constraints: primary key constraints, unique key constraints, foreign key constraints, NOT NULL constraints, and check constraints.  

    1. Primary Key Constraints

    A primary key constraint (also known as a "primary key") is a type of key constraint that requires every value in a given column to be unique. In other words, no two rows in a table can have the same value for their primary key column(s). A primary key can either be a single column or multiple columns (known as a "composite" primary key). The null value is not allowed in the primary key column(s).

    2. Unique Key Constraints

    A unique key constraint is a column or set of columns that ensures that the values stored in the column are unique. A table can have more than one unique key constraint, unlike the primary key. A unique key column can contain NULL values. Like primary keys, unique keys can be made up of a single column or multiple columns.

    3. Foreign Key Constraints

    A foreign key constraint defines a relationship between two tables. A foreign key in one table references a primary key in another table. Foreign keys prevent invalid data from being inserted into the foreign key column. Foreign keys can reference a single column or multiple columns.

    4. NOT NULL Constraints

    A NOT NULL constraint is used to ensure that no row can be inserted into the table without a value being specified for the column(s) with this type of constraint. Thus, every row must have a non-NULL value for these columns.

    5. Check Constraints

    A check constraint enforces data integrity by allowing you to specify conditions that must be met for data to be inserted into a column. For example, you could use a check constraint to ensure that only positive integer values are inserted into a particular column. Check constraints are usually used in combination with other constraints (such as NOT NULL constraints) to enforce more complex rules.

    There are several different types of key constraints in DBMS that you can use in SQL databases. Each type of constraint has its own specific use cases and benefits. By understanding when to use each type of constraint, you can ensure that your database is both reliable and consistent. For in-depth knowledge of the types of integrity constraints, you can go for the MongoDB Administration certification & expand your knowledge and develop a stronger outlook.

    Advantages of Integrity Constraints

    Integrity constraints in DBMS can be used to enforce rules at the database level, which means that they are applied to all users and applications that access the database. There are several advantages to using integrity constraints in SQL, which will be outlined in more detail below.

    1. Declarative Ease 

    One of the advantages of integrity constraints is that they can be declared easily. Integrity constraints are written in a declarative language, which means that they can be specified without having to write code. This makes it easy for even non-technical users to understand and specify rules.

    2. Centralized Rules

    Another advantage of integrity constraints is that they provide a centralized way to specify rules. Therefore, rules only have to be specified once and then they can be enforced across the entire database. This is much more efficient than having to specify rules individually for each application or user.

    3. Flexibility When Loading Data

    Integrity constraints also provide flexibility when loading data into the database. When data is loaded into the database, the integrity constraints are checked automatically. In other words, if there are any problems with the data, they can be detected and corrected immediately.

    4. Maximum Application Development Productivity

    Using integrity constraints can also help to maximize application development productivity. This is because developers do not have to write code to enforce rules; they can simply specify the rules using an integrity constraint language. This saves time and effort during development and makes it easier to create consistent and reliable applications.

    5. Immediate User Feedback

    Finally, using integrity constraints in DBMS provides immediate feedback to users when they attempt to violate a rule. For example, if a user tries to insert an invalid value into a database column, the database will reject the attempted insertion and return an error message to the user instead. This provides a clear indication to the user that their input is incorrect and needs to be corrected.

    Why are Integrity Constraints Important?

    Integrity constraints are important for several reasons. First, they help to ensure the accuracy of data by preventing invalid data from being entered into the database. Second, they help to maintain the consistency of data by ensuring that data is consistent across different tables and fields. Third, they help to prevent unauthorized access to data by ensuring that only authorized users can access specific data.

    Finally, they help to optimize performance by ensuring that only valid data is accessed and processed. By enforcing integrity constraints, databases can maintain a high level of accuracy and consistency while also preventing unauthorized access and optimizing performance.

    Conclusion

    Integrity constraints are a set of rules that help to maintain the accuracy and consistency of data in a database. There are several different types of integrity constraints in SQL, but all serve the same purpose: ensuring that the data in the database is reliable and accurate. In this article, we’ve given you a complete guide to understanding integrity constraints and how they work.

    We hope you found it helpful. If you have any questions about integrity constraints or want to learn more about how they can benefit your business, please don’t hesitate to take the KnowledgeHut MongoDB Professional certification. With their experts and curated study guides, you will learn all the skills proficiently.

    Frequently Asked Questions (FAQs)

    1What are data integrity constraints in DBMS used for?

    Data integrity constraints are used to maintain consistency and accuracy in database data. In addition to ensuring that records have unique IDs, they can also ensure that dates are correctly formatted. Constraints can also be used to limit the values that can be stored in a field or to ensure that certain relationships between fields are maintained. By carefully defining data integrity constraints, DBAs can help to ensure that the data in their databases is of high quality and can be relied upon by applications and users.

    2What are constraints in SQL with an example? 

    Constraints are conditions that must be met in order for a database operation to be successful. For example, a primary key constraint ensures that each row in a table has a unique ID, while a foreign key constraint ensures that each row in a table references a valid row in another table. By carefully defining constraints, database administrators can ensure that data is entered correctly and consistently.

    3What are the 5 major constraints used in SQL?

    The 5 major constraints used in SQL are: NOT NULL, CHECK, UNIQUE, PRIMARY KEY, and FOREIGN KEY. NOT NULL ensures that a column cannot store a NULL value. CHECK confirms that all values in a column meet a specified condition. UNIQUE guarantees that all values in a column are unique. PRIMARY KEY makes sure that a column can only store unique values. Finally, FOREIGN KEY enables all values in a column match the values in another column in another table. By using these constraints, SQL can ensure the integrity of data and prevent accidental modification or deletion of data.

    Profile

    Abhresh Sugandhi

    Author

    Abhresh is specialized as a corporate trainer, He has a decade of experience in technical training blended with virtual webinars and instructor-led session created courses, tutorials, and articles for organizations. He is also the founder of Nikasio.com, which offers multiple services in technical training, project consulting, content development, etc.

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