4.20 SQL-schemas

An SQL-schema is a persistent descriptor that includes:
 - The name of the SQL-schema.
 - The <authorization identifier> of the owner of the SQL-schema.
 - The name of the default character set for the SQL-schema.
 - The <schema path specification> defining the SQL-path for SQL-invoked routines for the SQL-schema.
 - The descriptor of every component of the SQL-schema.

In this part of ISO/IEC 9075, the term "schema" is used only in the sense of SQL-schema. The persistent objects described by the descriptors are said to be owned by or to have been created by the <authorization identifier> of the schema. Each component descriptor is one of:
 - A domain descriptor.
 - A base table descriptor.
 - A view descriptor.
 - A constraint descriptor.
 - A privilege descriptor.
 - A character set descriptor.
 - A collation descriptor.
 - A transliteration descriptor.
 - A user-defined type descriptor.
 - A routine descriptor.
 - A sequence generator descriptor.

A schema is created initially using a <schema definition> and may be subsequently modified incrementally over time by the execution of <SQL schema statement> s. <schema name> s are unique within a catalog. A <schema name> is explicitly or implicitly qualified by a <catalog name> that identifies a catalog. Base tables and views are identified by <table name> s. A <table name> consists of a <schema name> and an <identifier> . The <schema name> identifies the schema in which a persistent base table or view identified by the <table name> is defined. Base tables and views defined in different schemas can have <identifier> s that are equal according to the General Rules of Subclause 8.2, "<comparison predicate> ".

If a reference to a <table name> does not explicitly contain a <schema name> , then a specific <schema name> is implied. The particular <schema name> associated with such a <table name> depends on the context in which the <table name> appears and is governed by the rules for <schema qualified name>. If a reference to an SQL-invoked routine that is contained in a <routine invocation> does not explicitly contain a <schema name> , then the SQL-invoked routine is selected from the SQL-path of the schema. The containing schema of an <SQL schema statement> is defined as the schema identified by the <schema name> implicitly or explicitly contained in the name of the object that is created or manipulated by that SQLstatement.