Oracle - Identifiers

This article describes identifiers in Oracle.

Identifiers rules

Oracle - Identifier
First Character	An alphabetical character
Subsequent Characters	Alphanumeric characters, the underscore (_), dollar sign ($), and pound sign (#)
Maximum Length	30 bytes Database name is limited to 8 bytes, database links can be as long as 128 bytes
Case Sensitivity	Identifiers are not case sensitive, Oracle interprets them as uppercase in catalog views
Standards	ANSI SQL - $ is not allowed

Identifiers - Differences between Oracle and other Databases

Database	Identifiers	First Character	Subsequent Characters	Max Length
SQL Server	SQL Server Identifiers	Allowed: _ , @ and #	Allowed: @	128
IBM DB2	IBM DB2 Identifiers	No differences	Not allowed: @, # and $	128
MySQL	MySQL Identifiers	Allowed: digit	Not allowed: #	64
PostgreSQL	PostgreSQL Identifiers	Allowed: _	Not allowed: #	63
Sybase ASE	Sybase ASE Identifiers	Allowed: _ , @ and #	Allowed: @	255
Sybase ASA	Sybase ASA Identifiers	Allowed: _ , $, @ and #	Allowed: @	128
Informix	Informix Identifiers	Allowed: _	Not allowed: #	128
Teradata	Teradata Identifiers	Allowed: _, $ and #	No differences	30
HP Neoview	HP Neoview Identifiers	No differences	Not allowed: # and $	128
Interbase/Firebird	Interbase/Firebird Identifiers	No differences	Not allowed: #	67

Oracle - Quoted Identifiers
Quotation Marks	Double quotation marks ("")
Characters	Any character except double quotation marks and the null character (\0)
Maximum Length	30 bytes not including quotes
Case Sensitivity	Case sensitive

Quoted Identifiers - Differences between Oracle and other Databases

Database	Identifiers	Quotation Marks	Characters	Case Sensitivity
SQL Server	SQL Server Quoted Identifiers	[] and ""	Any except quotes	Case insensitive
IBM DB2	IBM DB2 Quoted Identifiers	""	Any including quotes	Case sensitive
MySQL	MySQL Quoted Identifiers	`` and ""	Any except quotes	Case sensitive
PostgreSQL	PostgreSQL Quoted Identifiers	""	Any including quotes	Case sensitive
Sybase ASE	Sybase ASE Quoted Identifiers	[] and ""	Any except pound sign (#) as the first character	Case insensitive
Sybase ASA	Sybase ASA Quoted Identifiers	[] and ""	Any	Case insensitive
Informix	Informix Quoted Identifiers	""	Any including quotes	Case sensitive
Teradata	Teradata Quoted Identifiers	""	Any including quotes	Case insensitive
HP Neoview	HP Neoview Quoted Identifiers	""	Any except at sign (@), forward slash (/), circumflex character (^) as the first character and space(s) as the last character(s)	Case sensitive
Interbase/Firebird	Interbase/Firebird Quoted Identifiers	""	Any character except space(s) as the last character(s)	Case sensitive