what is the query to delete first row in table
i have table with four column.. username , datetime,address
first when i insert first record, i have to check whether username available or not , if user name is not available , the record will insert..
if the same user insert their record .. i have to check the condition
if username not equal to 5 , the record will insert
if username equal to 5 , i have to delete first record based on the first datetime value