- ISO/IEC 9075 defines Structured Query Language (SQL). The scope of SQL is the definition of data structure and the operations on data stored in that structure. ISO/IEC 9075-1, ISO/IEC 9075-2 and ISO/IEC 9075-11 encompass the minimum requirements of the language. Other parts define extensions. ISO/IEC 9075-11 2011 specifies an Information Schema and a Definition Schema that describes the structure and integrity constraints of SQL-data, the security and authorization specifications relating to SQL-data and the features supported by an SQL-implementation together with other sizing information.