In Oracle, UPDATE statement is used to update the existing records in a table. You can update a table in 2 ways.
UPDATE table SET column1 = expression1, column2 = expression2, ... column_n = expression_n WHERE conditions;
UPDATE table1 SET column1 = (SELECT expression1 FROM table2 WHERE conditions) WHERE conditions;
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.
UPDATE suppliers SET supplier_name = 'Kingfisher' WHERE supplier_id = 2;
This example will update the supplier_name as "Kingfisher" where "supplier_id" is 2.
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;
UPDATE customers SET name = (SELECT supplier_name FROM suppliers WHERE suppliers.supplier_name = customers.name) WHERE age < 25;
Here, the customers table is updated by fetching the data from "suppliers" table.