Answers for "mysql select without duplicate rows"

mysql delete duplicate rows but keep one

DELETE c1 FROM contacts c1
INNER JOIN contacts c2 
WHERE
    c1.id > c2.id AND 
    c1.email = c2.email;

duplicate row mysql

# Duplicate rows or row
INSERT INTO table (col1, col2, col3)
SELECT col1, col2, col3 FROM table
WHERE something...;