SQL Basics
Querying Data
Filtering Data
Joining Tables
SQL Functions
Modifying Data
Defining Data
SQL UPDATE
In this tutorial, you will learn how to modify your existing rows in the database table using the SQL UPDATE statement.
Syntax
The basic syntax of the UPDATE statement to modify rows in table, can be given with:
UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition
Examples
To understand the UPDATE statement in a better way, let’s look at the following customers and orders tables in our tutorial database:
Now, let’s check out some examples that demonstrate how it actually works.
We have the following task be to solve using SQL statements
The following Query will returns all the rows from customers table.
UPDATE customers
SET country = 'Germany'
WHERE customer_id = 7
After executing the above query, you’ll get the result set something like this:
UPDATE customers
SET country = 'USA',
score = 100
WHERE customer_id = 6
As you can see the output contains everything the whole customers tables including all rows and columns.
Let’s say we are only interested in getting only specific columns from a table, then we could use the following syntax of the SELECT statement:
We have the following task to be solve using SQL statements
In the task we dont reuqire all the data, we need only specific columns. The following SQL statement selcts only first_name and country from table customers.
UPDATE customers
SET score = score + 50
After executing the above query, you’ll get the result set something like this:
As you can see the result contains only the columns that we specified after SELECT.
SELECT * helps you to examine the content of table that you are not familiar with. But be careful using it specially with big tables because database will retrieve everything which costs a lot of data movement across the network and might slow down the application
