SQL ET POSTGRE 4.16 : Introduction CRUD creation search modification and deletion of data

Welcome to this new section on the Data Manipulation Language, which covers inserting, modifying and deleting records in a database. So far we have learned how to define the structure of a database with the Data Definition Language — creating tables, altering columns, dropping tables. Now we are going to learn how to populate and maintain the data inside those structures.

What you will learn in this section

The first step is inserting data into a table using INSERT INTO. Once data is in place, we will see how to update it with UPDATE ... SET ... WHERE ... so we can fix a typo, change a status or push new values into specific rows. We will then learn how to remove rows using DELETE FROM ... WHERE ..., and how to wipe an entire table when needed. Each statement comes with safety reflexes, especially the WHERE clause, which is what prevents you from modifying or deleting more rows than intended.
  • Insert rows with INSERT INTO.
  • Modify existing rows with UPDATE.
  • Delete rows with DELETE.
  • Apply everything to the film database we built earlier.
Finally, we will apply everything we have learned by inserting concrete data into the film database we created in the previous section — directors, actors, films and the junction table. That data set will then power all the queries, joins and aggregate functions later in the course. Let's get started.

Summary

This lesson introduces SQL CRUD operations—Create, Read, Update, and Delete—which form the foundation of data manipulation in databases. You will learn how to insert new records, modify existing data, and remove entries from tables, with practical examples using the films database created previously.

Key points

  • CRUD stands for Create (insert), Read (search), Update (modify), and Delete (remove) operations
  • Data Manipulation Language (DML) is essential for inserting and managing records in database tables
  • The films database from previous sections serves as the practical example for all CRUD operations
  • Modification includes updating existing data to reflect changes or corrections
  • Deletion allows removing unwanted or obsolete records from your database

FAQ

What does CRUD stand for and why is it important?

CRUD stands for Create, Read, Update, and Delete. These four operations are the core functions for managing any database, allowing you to insert new data, retrieve existing records, modify information, and remove data as needed.

What database will we use for examples in this lesson?

This lesson uses the films database that you created in the previous sections of the course, applying CRUD operations directly to real database structures.

What is the difference between inserting and updating data?

Inserting (Create) adds entirely new records to a table, while updating (Modify) changes the values of existing records already stored in the database.