These warnings usually mean you are inserting a string into a column that's not wide enough.
for example: putting "hello I am here" into a varchar(5) will give an error because after 5 chars, mysql assumes the next column will begin. As this long string spans over the width of the column, it effectively increases the number of columns in your textfile by one.
You now hate one column too many, time for a warning.
The MySQL manual says this about warnings:
-- quote --
Warnings occur under the same circumstances as when values are inserted via the INSERT statement (see section 7.21 INSERT Syntax), except that LOAD DATA
INFILE also generates warnings when there are too few or too many fields in the input row. The warnings are not stored anywhere; the number of warnings
can only be used as an indication if everything went well. If you get warnings and want to know exactly why you got them, one way to do this is to use SELECT
... INTO OUTFILE into another file and compare this to your original input file.
-- end quote --
