12.4. SQL: Identifiers and Data Types
For a given schema, some database objects such as base tables, views, domains, and constraints are identified by name. A column is identified by appending its (local) name to the name of its table, using a “dot notation”. This distinguishes columns with the same local name in different tables. For example, the second columns of the tables Subject ( subiectCode, title, credit) and Book ( isbn, title) are identified as “Subject.title” and “Book.title”, respectively. In SQL, all names (including local names) are called identifiers, even though local names provide identification only within a limited context.
In SQL-89, identifiers were restricted to at most 18 characters, and all letters had to be in uppercase. ...
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