Teradata Keyword Compatibility Reference

Generated for GSP Java version 4.1.0.8 on 2026-03-15

This page was generated using hybrid static extraction from parser source files combined with runtime validation against the actual GSP parser. Re-run the extraction script after parser updates to keep this page current.

Keyword-as-Column-Name Support

As of version 4.1.0.8, the GSP Teradata parser includes a lexer lookahead mechanism that allows 46 vendor-unreserved keywords to be used as unquoted column names in SELECT statements.

The lookahead pre-scans the token list before parsing and converts context-specific keywords to identifiers when they appear in column-name position:

• After: SELECT, ,, DISTINCT, or ALL
• Before: FROM, AS, WHERE, GROUP, ORDER, HAVING, LIMIT, UNION, INTERSECT, EXCEPT, INTO, ,, ), or ;

-- Works: keyword as column name
SELECT add_months FROM t;

-- Works: keyword as column name
SELECT and FROM t;

-- Works: keyword as column name
SELECT begin FROM t;

-- Original keyword syntax also still works

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Full Classification Overview

Out of 702 keywords recognized by the GSP Teradata parser:

Classification	Count	Description
Allowed	652	Can be used as an unquoted column name in both canonical contexts
Context-specific	48	Fails as SELECT keyword FROM t but works as SELECT t.keyword FROM t
Blocked	2	Cannot be used as an unquoted column name in either context

Context-Specific Keywords (48)

These keywords fail when used as bare column names (SELECT keyword FROM t) but succeed when table-qualified (SELECT t.keyword FROM t).

Keyword	Reason
ADD_MONTHS	Grammar keyword
ALL	SELECT qualifier
AND	Operator keyword
BEGIN	Grammar keyword
CASE	Expression keyword
CASE_N	Grammar keyword
CAST	Expression keyword
CSUM	Grammar keyword
DISTINCT	SELECT qualifier
END	Grammar keyword
EXTRACT	Expression keyword
FIRST_VALUE	Grammar keyword
INTERVAL	Type keyword
JSON_AGG	Grammar keyword
JSON_COMPOSE	Grammar keyword
LAG	Grammar keyword
LAST_VALUE	Grammar keyword
LEAD	Grammar keyword
NEW	Grammar keyword
NEXT	Grammar keyword
NORMALIZE	Grammar keyword
NTH_VALUE	Grammar keyword
PERCENTILE_CONT	Grammar keyword
PERCENTILE_DISC	Grammar keyword
POSITION	Expression keyword
QUANTILE	Grammar keyword
RANGE_N	Grammar keyword
RANK	Grammar keyword
SUBSTR	Grammar keyword
SUBSTRING	Expression keyword
TIMESTAMP	Type keyword
TOP	SELECT qualifier
TRANSLATE	Grammar keyword
TRANSLATE_CHK	Grammar keyword
TRUNC	Grammar keyword
UNION	Clause keyword
UNIQUE	Grammar keyword
UPPER	Grammar keyword
XMLAGG	Grammar keyword
XMLCAST	Grammar keyword
XMLELEMENT	Grammar keyword
XMLFOREST	Grammar keyword
XMLROOT	Grammar keyword
XMLSERIALIZE	Grammar keyword
_GRAPHIC	Grammar keyword
_KANJISJIS	Grammar keyword
_LATIN	Grammar keyword
_UNICODE	Grammar keyword

Blocked Keywords (2)

These keywords cannot be used as unquoted column names in either context.

Keyword	Workaround
FROM	SELECT "from" FROM t
TRYCAST	SELECT "trycast" FROM t

Workaround: Double-Quoted Identifiers

For any keyword that fails as an unquoted column name, you can use double-quoted identifiers:

-- Blocked or context-specific keyword as column name
SELECT "from" FROM t;

-- Or use table qualification for context-specific keywords
SELECT t.add_months FROM t;

Scope and Limitations

• Tested contexts: SELECT keyword FROM t and SELECT t.keyword FROM t. Other contexts (DDL column definitions, INSERT column lists, aliases) may behave differently.
• Version-specific: This report reflects GSP Java version 4.1.0.8.
• Case sensitivity: Keywords are case-insensitive. select, SELECT, and Select are all treated the same.

How to Report Discrepancies

If you encounter a keyword that behaves differently from what this page describes, please report it through your support channel. Include:

1. The exact SQL statement
2. The GSP parser version
3. Whether the same SQL works in Teradata

Methodology

1. Static extraction: A Python script parses the lexer (.cod) and grammar (.y) source files to identify all 702 keywords and their grammar classifications.
2. Runtime validation: A Java test harness validates every classification against actual TGSqlParser runtime behavior.
3. JSON dataset: The authoritative data is stored in docs/generated/teradata_keyword_compatibility.json.