i ain't a database guy but here you go.

Theory
Core understanding of Database terms like
Schema, Table, Database Design Model(Physical model,Logical model), Relationship,
Constraints(primary key, Foreign Key and other constraints)
View, Triggers, Stored Procedures... ETC

Practical
Learn how to query to play around with data
Find on-line tutorials
http://www.w3schools.com/sql/


That's it
Once you get flexible with it,
You can learn about transaction and all other stuff
Dataware house
ETL
Big data



Youtube it,
Google it

Until you guys learn to search yourself to find the resources (what and how) you won't be able to conquer this.

sojoketo learnt and still learning everything on his own.
Ain't need any one else :P