We will get a list of id , name and length like this
1 John Deo 8
2 Max Ruin 8
3 Arnold 6
We can also use length in numeric field like this
SELECT id, name, length(name),length(mark) FROM `student`
Now let us try to find some blank data using length query
SELECT id, name FROM `student` where length(mark) <=1
This will display records where Mark is single digit or not entered.
What is the difference between length and char_length ?
Length returns string measured in bytes, but char_length returns number of characters. All chars does not occupy single byte particularly Unicode where chars are encoded in two bytes.
Here is an example.