SQL was adopted as a standard by the American National Standards Institute (ANSI) in 1986 as SQL-86 and International Organization for Standardization (ISO) in 1987
there are some of them : sql 89, sql 92, sql 99 and Tsql.
if someone know the differences between them reply to this thread.
Joins like Outer Join were being added in SQL 92. More on business analytics was focused in SQL 99. SQL/PSM and common table expressions were also added in SQL 99.