I'm a little confused about ANSI and sql. Is the ansi/sql relationship the same as posix/unix? Is sql language an ansi standard?
ANSI is the "American National Standards Institute". They are and organisation that defines standards for a very wide range of things: "from acoustical devices to construction equipment, from dairy and livestock production to energy distribution, and many more." About ANSI
SQL is a standard language for communicating with databases. This standard is defined by the American National Standards Institute in ISO/IEC 9075 and related documents.
One (of many) good source of practical information about SQL can be found at w3schools.com