Update your data

Applying SQL to Real-World Problems

Dmitriy (Dima) Gorenshteyn

Lead Data Scientist, Memorial Sloan Kettering Cancer Center

UPDATE syntax

UPDATE table_name
SET column1 = value1, column2 = value2, ...;

Desired Update: Emails of customers must be lowercase.

UPDATE customer
SET email = LOWER(email);

Desired Update: Emails of customers must be lowercase for customers who are still active.

UPDATE customer
SET email = LOWER(email)
WHERE active = TRUE;

Desired Update: Emails of customers must be lowercase for customers reside in city of Woodridge.

UPDATE customer
SET email = LOWER(email)
WHERE address_id IN 
  (SELECT address_id 
   FROM address
   WHERE city = 'Woodridge');

Ensure you CAN modify the table.
Ensure you know how this table is used and how your changes will impact those who use it.
Test a modification by using a SELECT statement first.

Applying SQL to Real-World Problems