Python Data Persistence – UPDATE Statement
It is possible to modify data of a certain field in a given table using the UPDATE statement. The usage syntax of the UPDATE query is as follows:
Example
UPDATE table_name SET coll=vall, col2=val2,.., colN=valN WHERE [expression] ;
Note that the WHERE clause is not mandatory when executing the UPDATE statement. However, you would normally want to modify only those records that satisfy ing a certain condition. If the WHERE clause is not specified, all records will be modified.
For example, the following statement changes the price of ‘Printer’ to 1000Q.
sqlite> update products set price=10000 where name='Printer';
sqlite> select * from products;
Product ID Name Price
---------- ----------- ------
1 Laptop 25000
2 TV 40000
3 Router 2000
4 Scanner 5000
5 Printer 10000
6 Mobile 15000However, if you want to increase the price of each product by 10 percent, you don’t have to specify the WHERE clause.
sqlite> update products set price=price+price*10/100;
sqlite> select * from products;
ProductID Name Price
---------- ---------- -------
1 Laptop 27500
2 TV 44000
3 Router 2200
4 Scanner 5500
5 Printer 11000
6 Mobile 16500