1. 利用insert ignore into語句去重

mysql> INSERT IGNORE INTO person_tbl (last_name, first_name)
    -> VALUES( ‘J‘, ‘T‘);
Query OK, 1 row affected (0.00 sec)
mysql> INSERT IGNORE INTO person_tbl (last_name, first_name)
    -> VALUES( ‘J‘, ‘T‘);
Query OK, 0 rows affected (0.00 sec)

2.查詢過濾重復數據

①. 利用MySQL的關鍵字DISTINCT去重

mysql> SELECT DISTINCT last_name, first_name
    -> FROM person_tbl;

②. 利用group by進行去重

mysql> SELECT last_name, first_name
    -> FROM person_tbl
    -> GROUP BY (last_name, first_name);

3. 刪除表中的重復數據

思路：先建一個臨時表，把不重復的數據數據存放在臨時表中，然後將原表刪除，再將臨時表rename成正式表

mysql> CREATE TABLE tmp SELECT
 
 last_name, first_name, sex FROM person_tbl  GROUP BY (last_name, first_name, sex);
mysql> DROP TABLE person_tbl;
mysql> ALTER TABLE tmp RENAME TO person_tbl;

mysql插入數據時，去掉重復的數據；