sql去重，同一个字段出现多条取一条的sql语句

1.某字段重复，其他字段值不同时，按重复字段分组只取一条的sql语句

select b.* from
(SELECT a.*,row_number() over (partition by a.column )as group_idx
FROM table_name a )b
where b.group_idx = \'1\'

2、某字段重复，其他字段值不同时，按重复字段分组只取一条的sql语句，数据又根据某字段排序

select b.* from
(SELECT a.*,row_number() over (partition by a.column1 order by a.column2 desc)as group_idx
FROM table_name a )b
where b.group_idx = \'1\'