Identifiers
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 backtick
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);
org.apache.spark.sql.catalyst.parser.ParseException:
no viable alternative at input 'CREATE TABLE test (a.'(line 1, pos 20)
-- 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);
org.apache.spark.sql.catalyst.parser.ParseException:
no viable alternative at input 'CREATE TABLE test (`a`b`'(line 1, pos 23)
-- This CREATE TABLE works
CREATE TABLE test (`a``b` int);