19.8. Inserting, Updating, and Deleting Records

PreparedStatement pstmt = con.prepareStatement("INSERT INTO students VALUES (?, ?, ?);");
pstmt.setInt(1, 103);
pstmt.setString(2, "Aman");
pstmt.setString(3, "B.Tech");
int rows = pstmt.executeUpdate();
System.out.println(rows + " rows inserted.");

In this chunk, we cover the process of inserting records into a database using JDBC. First, we prepare a SQL statement that defines how we want to insert data into the 'students' table. We use placeholders (question marks) to indicate where data will be inserted. We then set the actual values for these placeholders using the setInt and setString methods. Finally, we execute the update using executeUpdate(), which returns the number of rows affected by the operation, allowing us to confirm how many records were inserted.

Think of this process like filling out a form for a new student at a school. Just as you fill in different fields like ID, name, and course, here we define the data we want to insert into our database. Once the form is complete and submitted, the student is officially added to the school records just like our data is added to the database.

PreparedStatement pstmt = con.prepareStatement("UPDATE students SET name=? WHERE id=?;");
pstmt.setString(1, "Rahul");
pstmt.setInt(2, 101);
pstmt.executeUpdate();

In this section, we discuss how to update existing records in the database. We prepare a SQL statement for updating a specific student's name based on their ID. Just as before, we use placeholders, but in this case, we specify the new name and the ID of the student we want to update. The executeUpdate() method is used again to perform the operation, updating the necessary record in the database.

Consider this updating process as changing your contact details with a service provider. You provide the updated name (new contact detail) along with your unique account ID (identification), and once you submit the update, they modify their records accordingly. Similarly, we’re modifying the student details in the database.

PreparedStatement pstmt = con.prepareStatement("DELETE FROM students WHERE id=?;");
pstmt.setInt(1, 101);
pstmt.executeUpdate();

This chunk explains how to delete records from the database. We prepare a SQL statement that specifies which record to remove by identifying it with an ID. Using the setInt method, we provide the ID of the student we wish to delete. The executeUpdate() method executes the deletion. Just like insertion and updating, this method affects the number of records removed from the table.

Think of deleting a record like removing a page from a book. When you realize a page is no longer needed (for example, if a student leaves the school), you simply rip it out. In our case, we identify the specific page (student record) to remove using its ID and then execute the deletion process.

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