如果字符串超过一定数量的字符，如何用MySQL回显部分UTF-8 varchar字符串？

I'm currently using the substr() function which works fine for characters written in english. But when I apply that to characters written in greek, the text is cut with a strange character (a questionmark inside a diamond shape) appearing before the 3 fullstops (...). Below is the code, thanks:I'm currently using the substr() function which