text: -- @testpoint: 最后一个字符做分隔符
  DROP TABLE IF EXISTS type_char;
  CREATE TABLE type_char (string1 char(100));
  insert into type_char values ('abc');
  SELECT split_part(string1,'c',1) from type_char;
  SELECT split_part(string1,'c',2) from type_char;
  DROP TABLE IF EXISTS type_char;