How to CRUD Operations in SQL| What Is CRUD?
There are four operations used by both database managers and developers while designing the software, such as the Create, Read, Update, and Delete operations. All interactions with the database, in addition to data manipulation inside the database, use one of the following multiple methods. You can, using CRUD operations in SQL, manipulate your data in the event of relational database work: MySQL, PostgreSQL, SQL Server, among others.
We will analyze how SQL commands are performed in each operation.
What Is CRUD?
1. Create (INSERT)
Add new data into a table is referred to as a "create". With SQL, an INSERT statement is used with the purpose of adding more than one row to a table of a database. As an example:
INSERT INTO customers (first_name, last_name, email)
VALUES ('John', 'Doe', 'john.doe@example.com');
The customers table is the one where we are inserting data to.
(first_name, last_name, email) refers to the column where we are inserting values to.
VALUES ('John', 'Doe', 'john.doe@example.com') are actual values we are inserting in the table.
2. Read (SELECT)
SELECT * FROM customers;
If you want to retrieve a specific column, for instance, first_name and email, you can modify your query like this:
SELECT first_name, email FROM customers;
You can also filter the data by using the WHERE clause:
SELECT * FROM customers WHERE last_name = 'Doe';
This query fetches all customers whose last name is "Doe".
3. Update (UPDATE)
The "Update" operation is an operation that changes the existing data in the database. It is done using the UPDATE statement. Here is an example of updating a customer's email address:
UPDATE customers
SET email = 'new.email@example.com'
WHERE customer_id = 1;
Here is what's happening in this query:
UPDATE customers specifies the table to update.
SET email = 'new.email@example.com' defines the new value for the email column.
WHERE customer_id = 1 ensures that only the customer with customer_id 1 gets updated.
Tip: Always provide a WHERE clause with the UPDATE clause to avoid unwanted updating all rows in a table by mistake.
4. Deleting (DELETE)
DELETE operation removes information from your database. SQL deletes one, two, or more records with DELETE statement. There is no example for this here as:.
Tipp: Like with UPDATE using the WHERE clause is unavoidable in DELETE to avoid changing all the records by error.
Best Practices for performing CRUD Operations in SQL.
Backup Your Data: This one is important before performing a type of UPDATE or DELETE just in case you change an important record accidentally and that causes you to lose part or completely lose your data.
Make use of Transactions: Where you are working on multi INSERT, UPDATE, and DELETE statements, you MUST wrap them in a TRANSACTION (BEGIN TRANSACTION, COMMIT, ROLLBACK to ensure data consistency.
Use Constraints: Use primary keys, foreign keys, and unique constraints to maintain data integrity against duplication or accidental deletion.
Be Performance Aware: Use proper indexing and filtering methods to optimize your SELECT queries to avoid slow queries especially when dealing with large data sets.
Conclusion
CRUD operations form the backbone of databases and SQL. Building a web application or handling data for a business requires knowing the appropriate use of INSERT, SELECT, UPDATE, and DELETE for data management. The effective use of these SQL commands ensures your database performs well and data integrity is maintained by following best practices.
Practice all these operations by working through a test database, trying more complex queries, and you will significantly enhance your database management capabilities with mastery of CRUD.
