3-3 SQL Commands Explained

Key Concepts

• SELECT
• INSERT
• UPDATE

SELECT

The SELECT command is used to retrieve data from a database. It allows you to specify which columns you want to retrieve and from which table. You can also use conditions to filter the data using the WHERE clause.

Example: To retrieve all the names and grades of students from a "Students" table, you would use the following SQL command:

        SELECT Name, Grade 
        FROM Students;
    

Analogy: Think of SELECT as picking specific items from a grocery list. You can choose to pick only the fruits or vegetables, or you can pick everything, depending on your needs.

INSERT

The INSERT command is used to add new records into a table. You specify the table name and the values you want to insert into the new record. This command is essential for populating a database with new data.

Example: To add a new student with the name "John Doe" and a grade of "A" into the "Students" table, you would use the following SQL command:

        INSERT INTO Students (Name, Grade) 
        VALUES ('John Doe', 'A');
    

Analogy: Think of INSERT as adding new items to your grocery list. Each time you remember something you need, you add it to the list.

UPDATE

The UPDATE command is used to modify existing records in a table. You specify the table name, the columns you want to update, and the new values. You can also use conditions to specify which records should be updated using the WHERE clause.

Example: To update the grade of a student named "John Doe" to "B" in the "Students" table, you would use the following SQL command:

        UPDATE Students 
        SET Grade = 'B' 
        WHERE Name = 'John Doe';
    

Analogy: Think of UPDATE as changing items on your grocery list. If you decide you no longer need apples but want oranges instead, you update the list accordingly.

Conclusion

Understanding these three SQL commands—SELECT, INSERT, and UPDATE—is fundamental for interacting with databases. They allow you to retrieve, add, and modify data, respectively, making your database management tasks more efficient and effective.