text: -- @testpoint: 匹配逃逸字符本身
  DROP TABLE IF EXISTS type_char;
  CREATE TABLE type_char (string1 char(100));
  insert into type_char values ('AA@_BBCC');
  SELECT  (string1 LIKE '%A@@_B%' ESCAPE '@') from type_char AS RESULT;
  DROP TABLE IF EXISTS type_char;