如何在MySql SELECT语句中正确使用LIKE语句？

Why isn't this working?

为什么这不起作用?

DELIMITER ;//

CREATE PROCEDURE `blah`
(
  SearchText varchar(4000)
)
BEGIN
  SELECT *
  FROM table_name
  WHERE table_name.StringField LIKE '%' + SearchText + '%'; -- This is where the code is breaking
END;//
DELIMITER