MySQL: Remove duplicate string-introducer arm

src/parser/mod.rs

@@ -1720,17 +1720,6 @@ impl<'a> Parser<'a> {
                     value: self.parse_introduced_string_expr()?.into(),
                 })
             }
-            // string introducer https://dev.mysql.com/doc/refman/8.0/en/charset-introducer.html
-            Token::SingleQuotedString(_)
-            | Token::DoubleQuotedString(_)
-            | Token::HexStringLiteral(_)
-                if w.value.starts_with('_') =>
-            {
-                Ok(Expr::Prefixed {
-                    prefix: w.to_ident(w_span),
-                    value: self.parse_introduced_string_expr()?.into(),
-                })
-            }
             // An unreserved word (likely an identifier) is followed by an arrow,
             // which indicates a lambda function with a single, untyped parameter.
             // For example: `a -> a * 2`.

tests/sqlparser_mysql.rs

@@ -3805,6 +3805,7 @@ fn parse_string_introducers() {
     mysql().verified_stmt("SELECT _binary 'abc'");
     mysql().one_statement_parses_to("SELECT _utf8'abc'", "SELECT _utf8 'abc'");
     mysql().one_statement_parses_to("SELECT _utf8mb4'abc'", "SELECT _utf8mb4 'abc'");
+    mysql().one_statement_parses_to("SELECT _utf8mb4\"abc\"", "SELECT _utf8mb4 \"abc\"");
     mysql().verified_stmt("SELECT _binary 'abc', _utf8mb4 'abc'");
 }