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SQL QuizSQL UPDATE Statement
The UPDATE statement is used to update records in a table.
The UPDATE Statement
The UPDATE statement is used to update existing records in a table.
SQL UPDATE Syntax
UPDATE table_name
SET column1=value, column2=value2,...
WHERE some_column=some_value
SET column1=value, column2=value2,...
WHERE some_column=some_value
Note: Notice the WHERE clause in the UPDATE syntax. The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!
SQL UPDATE Example
The "Persons" table:
| P_Id | LastName | FirstName | Address | City |
|---|---|---|---|---|
| 1 | Hansen | Ola | Timoteivn 10 | Sandnes |
| 2 | Svendson | Tove | Borgvn 23 | Sandnes |
| 3 | Pettersen | Kari | Storgt 20 | Stavanger |
| 4 | Nilsen | Johan | Bakken 2 | Stavanger |
| 5 | Tjessem | Jakob |
Now we want to update the person "Tjessem, Jakob" in the "Persons" table.
We use the following SQL statement:
UPDATE Persons
SET Address='Nissestien 67', City='Sandnes'
WHERE LastName='Tjessem' AND FirstName='Jakob'
SET Address='Nissestien 67', City='Sandnes'
WHERE LastName='Tjessem' AND FirstName='Jakob'
The "Persons" table will now look like this:
| P_Id | LastName | FirstName | Address | City |
|---|---|---|---|---|
| 1 | Hansen | Ola | Timoteivn 10 | Sandnes |
| 2 | Svendson | Tove | Borgvn 23 | Sandnes |
| 3 | Pettersen | Kari | Storgt 20 | Stavanger |
| 4 | Nilsen | Johan | Bakken 2 | Stavanger |
| 5 | Tjessem | Jakob | Nissestien 67 | Sandnes |
SQL UPDATE Warning
Be careful when updating records. If we had omitted the WHERE clause in the example above, like this:
UPDATE Persons
SET Address='Nissestien 67', City='Sandnes'
SET Address='Nissestien 67', City='Sandnes'
The "Persons" table would have looked like this:
| P_Id | LastName | FirstName | Address | City |
|---|---|---|---|---|
| 1 | Hansen | Ola | Nissestien 67 | Sandnes |
| 2 | Svendson | Tove | Nissestien 67 | Sandnes |
| 3 | Pettersen | Kari | Nissestien 67 | Sandnes |
| 4 | Nilsen | Johan | Nissestien 67 | Sandnes |
| 5 | Tjessem | Jakob | Nissestien 67 | Sandnes |
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Copyright 1999-2012 by Refsnes Data. All Rights Reserved.
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.