No matter if you are programmer, data analysts or a end user, you would find learning SQL is important to execute your day to day tasks. SQL is the standard of querying your corporate database to get the insight information hidden in the storage.
Database vendors do have their own favor of SQL however most of them are SQL-92 compliant with few extra functions.
Below are the recommended books to learn SQL. These books are highly recommended on for everyone who wants to dig deeper in SQL.