SQL UPDATE

Once we have the information in the table, we might find that there is a need to modify the data. To do so, we can use the UPDATE command. The syntax for this is

 

 

It is easiest to use an example. Say we currently have a table as below:

Table Store_Information

store_nameSalesDate
Los Angeles$1500Jan-05-1999
San Diego$250Jan-07-1999
Los Angeles$300Jan-08-1999
Boston$700Jan-08-1999

We find that the sales for Los Angeles on 01/08/1999 is actually $500 instead of $300, and we need to update that particular entry. To do so, we use the following SQL:

 

 

The resulting table would look like

Table Store_Information

store_nameSalesDate
Los Angeles$1500Jan-05-1999
San Diego$250Jan-07-1999
Los Angeles$500Jan-08-1999
Boston$700Jan-08-1999

In this case, there is only one row that satisfies the condition in the WHERE clause. If there are two rows that satisfy the condition, both rows will be modified.

It is also possible to UPDATE multiple columns at the same time. The syntax, in this case, would look like the following: