sqlzoo.net
What is Sql?
SQL stands for "Structured Query Language". This language allows us to pose complex questions of a database. It also provides a means of creating databases. SQL very widely used. Many database products support SQL, this means that if learn how to use SQL you can apply this knowledge to MS Access or SQL Server or to Oracle or Ingres and countless other databases.
SQL works with relational databases. A relational database stores data in tables (relations). A database is a collection of tables. A table consists a list of records - each record in a table has the same structure, each has a fixed number of "fields" of a given type.......