UPDATE single column in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the SQL UPDATE statement do?

The UPDATE statement changes existing data in a table. It modifies one or more columns for rows that match a condition.

beginner

How do you update a single column in SQL?

Use UPDATE table_name SET column_name = new_value WHERE condition; to change one column's value in rows that meet the condition.

beginner

Why is the WHERE clause important in an UPDATE statement?

The WHERE clause limits which rows get updated. Without it, all rows in the table will be changed.

beginner

Write an example SQL query to update the salary column to 5000 for employees with id 3.

Example: <br>UPDATE employees SET salary = 5000 WHERE id = 3;

intermediate

What happens if you run UPDATE employees SET salary = 5000; without a WHERE clause?

All rows in the employees table will have their salary set to 5000, which might not be what you want.

Which SQL keyword is used to change data in a table?

A SELECT

B UPDATE

C INSERT

D DELETE

The UPDATE keyword modifies existing data in a table.

What does the WHERE clause do in an UPDATE statement?

A Specifies which rows to update

B Specifies which columns to update

C Creates a new table

D Deletes rows

The WHERE clause limits the rows affected by the update.

How do you update only the price column in a table named products?

A UPDATE products SET price = new_value;

B UPDATE products WHERE price = new_value;

C SELECT price FROM products;

D UPDATE products SET price = new_value WHERE condition;

You must use SET to specify the column and WHERE to limit rows.

What happens if you omit the WHERE clause in an UPDATE?

A All rows are updated

B Only one row is updated

C No rows are updated

D The query fails

Without WHERE, all rows in the table are updated.

Which of these is a valid SQL update statement for a single column?

A UPDATE table SET (column = value);

B UPDATE table WHERE id = 1 SET column = value;

C UPDATE table SET column = value WHERE id = 1;

D UPDATE table (column) VALUES (value);

The correct syntax is UPDATE table SET column = value WHERE condition;.

Explain how to update a single column in a SQL table safely.

Think about how to change only certain rows without affecting the whole table.

What could happen if you forget the WHERE clause in an UPDATE statement?

Consider the impact on the entire table.