查询表中是否存在重复数据（一个字段和 多个字段）

select * from crs_i18n where i18n_code in (
SELECT i18n_code FROM crs_i18n GROUP BY i18n_code HAVING COUNT(i18n_code)>1
);    //根据一个字段查询

SELECT    
*
FROM
crs_i18n a
WHERE
EXISTS (
SELECT
1
FROM
crs_i18n b
WHERE
a.i18n_code = b.i18n_code
AND a.cn_name = b.cn_name
HAVING
COUNT (*) > 1
)
ORDER BY
A.i18n_code;  //多个字段