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SQL UPDATE Statement

The SQL UPDATE Statement

The UPDATE statement is used to modify the existing records in a table.


UPDATE Syntax 

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition
Be careful when updating records in a table! Notice the WHERE clause in the UPDATE statement. The WHERE clause specifies which record(s) that should be updated. If you omit the WHERE clause, all records in the table will be updated!

Demo Database

Below is a selection from the "Customers" table in the Northwind sample database:

CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la ConstituciГіn 2222 MГ©xico D.F. 05021 Mexico
3 Antonio Moreno TaquerГ­a Antonio Moreno Mataderos 2312 MГ©xico D.F. 05023 Mexico
4 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

SQL UPDATE Table Example

The following SQL statement updates the first customer (CustomerID = 1) with a new contact person and a new city. 

UPDATE Customers 
SET ContactName = 'Alfred Schmidt', City = 'Frankfurt' 
WHERE CustomerID = 1

The selection from the "Customers" table will now look like this:

CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Alfred Schmidt Obere Str. 57 Frankfurt 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la ConstituciГіn 2222 MГ©xico D.F. 05021 Mexico
3 Antonio Moreno TaquerГ­a Antonio Moreno Mataderos 2312 MГ©xico D.F. 05023 Mexico
4 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

SQL UPDATE Multiple Records Example

It is the WHERE clause that determines how many records will be updated.

The following SQL statement will update the ContactName to "Juan" for all records where country is "Mexico": 

UPDATE Customers 
SET ContactName = 'Juan' 
WHERE Country = 'Mexico'

The selection from the "Customers" table will now look like this:

CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Alfred Schmidt Obere Str. 57 Frankfurt 12209 Germany
2 Ana Trujillo Emparedados y helados Juan Avda. de la ConstituciГіn 2222 MГ©xico D.F. 05021 Mexico
3 Antonio Moreno TaquerГ­a Juan Mataderos 2312 MГ©xico D.F. 05023 Mexico
4 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

Update Warning!

Be careful when updating records. If you omit the WHERE clause, ALL records will be updated! 
UPDATE Customers 
SET ContactName = 'Juan'

The selection from the "Customers" table will now look like this:

CustomerID CustomerName ContactName Address City PostalCode Country
1 Alfreds Futterkiste Juan Obere Str. 57 Frankfurt 12209 Germany
2 Ana Trujillo Emparedados y helados Juan Avda. de la ConstituciГіn 2222 MГ©xico D.F. 05021 Mexico
3 Antonio Moreno TaquerГ­a Juan Mataderos 2312 MГ©xico D.F. 05023 Mexico
4 Around the Horn Juan 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Juan Berguvsvägen 8 Luleå S-958 22 Sweden
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