Grokking SQL for Tech Interviews
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UPDATE
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UPDATE

Example

UPDATE

The UPDATE statement in SQL is used to modify existing records in a table. It allows you to change the values of one or more columns in a specific row.

The basic syntax for the UPDATE statement is as follows:

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

Let's break down the components of the UPDATE statement:

  • UPDATE: This keyword indicates that you want to update existing records in a table.
  • table_name: Specifies the name of the table.
  • SET: This keyword is followed by a list of columns and their new values. It indicates what values should be assigned to the specified columns.
  • column1 = value1, column2 = value2, ...: Specifies the columns to be updated and their new values. A comma separates each assignment.
  • WHERE: This optional clause allows you to specify conditions determining which records should be updated.
  • condition: The condition in the WHERE clause filters the records that should be updated.

Example

Suppose we have a table named employees with columns id, firstName, lastName, salary, and department_id,

Image

and you want to increase the salary by 50% for employees whose department_id is 2:

UPDATE employees
SET salary = salary * 2
WHERE department_id = 2;

In this example, the UPDATE statement increases employees' salaries in the specified department by multiplying their current salary by 2. The WHERE clause ensures that only records meeting the condition department_id = 2 are updated.

The updated employees table will look like this:

Image

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On this page

UPDATE

Example