• Open MySQL Workbench

• In order to UPDATE/DELETE rows without specifying keys (primary key) we need to disable safe mode in MySQL Workbench

  • In the top bar, select MySQL Workbench -> Preferences
  • Select "SQL Editor"
    • Note: there are three child dropdowns but just select the parent (SQL Editor)
  • Scroll to the bottom and deselect the checkbox that says "Safe Updates"

• Once safe mode is disabled you will need to disconnect and reconnect to your db

• Make sure you've selected the "admin" database

• Create a new query tab

  • Click the button on the top left that has a SQL file with a "plus" icon on it

• Click the folder icon in your query tab to open a new file

• Select the "initialize.sql" script that lives in this repo

• Click the lightning bolt icon to run the query

• If you refresh your schemas you should see a "users", "usersContact" and "usersAddress" table

We are going to run a couple INSERT/UPDATE/DELETE statements and put our SQL STATEMENTS in the "SQL" section of this README. The SQL instructions are intentionally written in plain english. It's up to you to translate that into the appropriate CRUD operations.

1. Insert users ('test', 'user') & ('test2', 'user') into the users table. Use a SELECT statment to verfiy the existence of the new ids 501 and 502. Record just the INSERT statement in the section below.

2. Pretend we are in the beginnings of an apocalyptic event. It started in Ohio. Update the usersAddress table and change every "address" in the state of OH to the text "REDACTED" since Ohio no longer exists. You should update 22 rows. Place this update statement in the section below.

3. Delete the user with the id of 114 from the users table.

Did the above statment fail? Why? What does the error response say?

We cannot delete this user yet because other tables (usersContact, usersAddress) are children of this table. Remember when we talked about foreign keys in the last lesson? That means we need to delete the appropriate information from those tables before we can delete the user.

This should make sense because we can't have user addresses that don't correspond to any user (since the user would have been deleted).

Let's delete the appropriate information from usersContact, usersAddress and finally users all corresponding to the user id of 114. Put all three DELETE statments below.

1. INSERT two users:

insert into users(first_name, last_name)
values ('test','user'), ('test2','user')

2. UPDATE all Ohio addresses to "REDACTED":

update usersAddress
set address = 'REDACTED'
where state = 'OH'

3. All three DELETES

• DELETE from usersContact

delete from usersContact where user_id = 114;

• DELETE from usersAddress

delete from usersAddress where user_id = 114;

• DELETE from users

delete from users where id = 114;

Make sure we understand these CRUD operations because soon we will be pulling these SQL commands into our Node/Express application.