Identifiers
Description
An identifier is a string used to identify a database object such as a table, view, schema, column, etc. Spark SQL has regular identifiers and delimited identifiers, which are enclosed within backticks. Both regular identifiers and delimited identifiers are case-insensitive.
Syntax
Regular Identifier
{ letter | digit | '_' } [ , ... ]
Note: If spark.sql.ansi.enabled
is set to true, ANSI SQL reserved keywords cannot be used as identifiers. For more details, please refer to ANSI Compliance.
Delimited Identifier
`c [ ... ]`
Parameters
-
letter
Any letter from A-Z or a-z.
-
digit
Any numeral from 0 to 9.
-
c
Any character from the character set. Use
`
to escape special characters (e.g.,`
).
Examples
-- This CREATE TABLE fails with ParseException because of the illegal identifier name a.b
CREATE TABLE test (a.b int);
Error in query:
[PARSE_SYNTAX_ERROR] Syntax error at or near '.': extra input '.'(line 1, pos 20)
== SQL ==
CREATE TABLE test (a.b int)
--------------------^^^
-- This CREATE TABLE works
CREATE TABLE test (`a.b` int);
-- This CREATE TABLE fails with ParseException because special character ` is not escaped
CREATE TABLE test1 (`a`b` int);
Error in query:
[PARSE_SYNTAX_ERROR] Syntax error at or near '`'(line 1, pos 24)
== SQL ==
CREATE TABLE test1 (`a`b` int)
------------------------^^^
-- This CREATE TABLE works
CREATE TABLE test (`a``b` int);