fix: allow string aliases closes #2788

tobymao · Jan 7, 2024 · d31ae0d · d31ae0d
1 parent 963e2dc
commit d31ae0d
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Showing 5 changed files with 31 additions and 1 deletion.
diff --git a/sqlglot/dialects/mysql.py b/sqlglot/dialects/mysql.py
@@ -443,6 +443,7 @@ class Parser(parser.Parser):
         }
 
         LOG_DEFAULTS_TO_LN = True
+        STRING_ALIASES = True
 
         def _parse_primary_key_part(self) -> t.Optional[exp.Expression]:
             this = self._parse_id_var()

diff --git a/sqlglot/dialects/sqlite.py b/sqlglot/dialects/sqlite.py
@@ -78,6 +78,7 @@ class Parser(parser.Parser):
             **parser.Parser.FUNCTIONS,
             "EDITDIST3": exp.Levenshtein.from_arg_list,
         }
+        STRING_ALIASES = True
 
     class Generator(generator.Generator):
         JOIN_HINTS = False

diff --git a/sqlglot/dialects/tsql.py b/sqlglot/dialects/tsql.py
@@ -467,6 +467,7 @@ class Parser(parser.Parser):
         LOG_DEFAULTS_TO_LN = True
 
         ALTER_TABLE_ADD_REQUIRED_FOR_EACH_COLUMN = False
+        STRING_ALIASES = True
 
         def _parse_projections(self) -> t.List[exp.Expression]:
             """

diff --git a/sqlglot/parser.py b/sqlglot/parser.py
@@ -958,6 +958,9 @@ class Parser(metaclass=_Parser):
     # Whether the TRIM function expects the characters to trim as its first argument
     TRIM_PATTERN_FIRST = False
 
+    # Whether or not string aliases are supported `SELECT COUNT(*) 'count'`
+    STRING_ALIASES = False
+
     # Whether query modifiers such as LIMIT are attached to the UNION node (vs its right operand)
     MODIFIERS_ATTACHED_TO_UNION = True
     UNION_MODIFIERS = {"order", "limit", "offset"}
@@ -4905,7 +4908,9 @@ def _parse_alias(
             self._match_r_paren(aliases)
             return aliases
 
-        alias = self._parse_id_var(any_token)
+        alias = self._parse_id_var(any_token) or (
+            self.STRING_ALIASES and self._parse_string_as_identifier()
+        )
 
         if alias:
             return self.expression(exp.Alias, comments=comments, this=this, alias=alias)

diff --git a/tests/dialects/test_dialect.py b/tests/dialects/test_dialect.py
@@ -1683,6 +1683,28 @@ def test_limit(self):
         )
 
     def test_alias(self):
+        self.validate_all(
+            'SELECT 1 AS "foo"',
+            read={
+                "mysql": "SELECT 1 'foo'",
+                "sqlite": "SELECT 1 'foo'",
+                "tsql": "SELECT 1 'foo'",
+            },
+        )
+
+        for dialect in (
+            "presto",
+            "hive",
+            "postgres",
+            "clickhouse",
+            "bigquery",
+            "snowflake",
+            "duckdb",
+        ):
+            with self.subTest(f"string alias: {dialect}"):
+                with self.assertRaises(ParseError):
+                    parse_one("SELECT 1 'foo'", dialect=dialect)
+
         self.validate_all(
             "SELECT a AS b FROM x GROUP BY b",
             write={