[mssql] Support single-quoted column aliases

src/sqlparser.rs

@@ -1167,15 +1167,18 @@ impl Parser {
             {
                 Ok(Some(w.as_sql_ident()))
             }
-            ref not_an_ident if after_as => parser_err!(format!(
-                "Expected an identifier after AS, got {:?}",
-                not_an_ident
-            )),
-            Some(_not_an_ident) => {
-                self.prev_token();
+            // MSSQL supports single-quoted strings as aliases for columns
+            // We accept them as table aliases too, although MSSQL does not.
+            Some(Token::SingleQuotedString(ref s)) => Ok(Some(format!("'{}'", s))),
+            not_an_ident => {
+                if after_as {
+                    return self.expected("an identifier after AS", not_an_ident);
+                }
+                if not_an_ident.is_some() {
+                    self.prev_token();
+                }
                 Ok(None) // no alias found
             }
-            None => Ok(None),
         }
     }
 

tests/sqlparser_common.rs

@@ -212,6 +212,21 @@ fn parse_column_aliases() {
     one_statement_parses_to("SELECT a.col + 1 newname FROM foo AS a", &sql);
 }
 
+#[test]
+fn test_eof_after_as() {
+    let res = parse_sql_statements("SELECT foo AS");
+    assert_eq!(
+        ParserError::ParserError("Expected an identifier after AS, found: EOF".to_string()),
+        res.unwrap_err()
+    );
+
+    let res = parse_sql_statements("SELECT 1 FROM foo AS");
+    assert_eq!(
+        ParserError::ParserError("Expected an identifier after AS, found: EOF".to_string()),
+        res.unwrap_err()
+    );
+}
+
 #[test]
 fn parse_select_count_wildcard() {
     let sql = "SELECT COUNT(*) FROM customer";

tests/sqlparser_mssql.rs

@@ -27,6 +27,11 @@ fn parse_mssql_identifiers() {
     };
 }
 
+#[test]
+fn parse_mssql_single_quoted_aliases() {
+    let _ = ms_and_generic().one_statement_parses_to("SELECT foo 'alias'", "SELECT foo AS 'alias'");
+}
+
 #[test]
 fn parse_mssql_delimited_identifiers() {
     let _ = ms().one_statement_parses_to(