In Oracle, UPDATE statement is used to update the existing records in a table. You can update a table in 2 ways.

Traditional Update table method

Syntax:

UPDATE table  
SET column1 = expression1,  
    column2 = expression2,  
    ...  
    column_n = expression_n  
WHERE conditions;  

Update Table by selecting rocords from another table

Syntax:

UPDATE table1  
SET column1 = (SELECT expression1  
               FROM table2  
               WHERE conditions)  
WHERE conditions;   

Parameters:

1- column1, column2, ... column_n:

It specifies the columns that you want to update.

2- expression1, expression2, ...expression_n:

This specifies the values to assign to the column1, column2, ?. column_n.

3- conditions:It specifies the conditions that must be fulfilled for execution of UPDATE stateme.

Oracle Update Example: (Update single column)

UPDATE suppliers  
SET supplier_name = 'Kingfisher'  
WHERE supplier_id = 2;  

This example will update the supplier_name as "Kingfisher" where "supplier_id" is 2.

Oracle Update Example: (Update multiple columns)

The following example specifies how to update multiple columns in a table. In this example, two columns supplier_name and supplier_address is updated by a single statement.

UPDATE suppliers  
SET supplier_address = 'Agra',  
    supplier_name = 'Bata shoes'  
WHERE supplier_id = 1;  

Output:

1 row(s) updated.
0.06 seconds

Oracle Update Example: (By selecting records from another table)

UPDATE customers  
SET name = (SELECT supplier_name  
                 FROM suppliers  
                 WHERE suppliers.supplier_name = customers.name)  
WHERE age < 25;  

Output:

2 row(s) updated.
0.02 seconds

Here, the customers table is updated by fetching the data from "suppliers" table.