SELECT

    fs.card_id,

    fs. NAME,

    fs.email,

    fs.phone_num,

    fs.weixin_num,

    fs.permission,

    fs.open_id

FROM

    fs_card fs

WHERE

    fs.open_id IS NOT NULL

GROUP BY fs.name having COUNT(fs.card_id)= 1

//加上count (fs.card_id)=1 条件后会把 具有相同名字的数据 去除（默认这两条数据的card_id 不同） 

SELECT

    fs.card_id,

    fs. NAME,

    fs.email,

    fs.phone_num,

    fs.weixin_num,

    fs.permission,

    fs.open_id

FROM

    fs_card fs

WHERE

    fs.open_id IS NOT NULL

GROUP BY fs.name having COUNT(fs.card_id)>= 1

//查询结果和 不加 having 条件 相同。

SELECT distinct

    fs.card_id,

    fs. NAME,

    fs.email,

    fs.phone_num,

    fs.weixin_num,

    fs.permission,

    fs.open_id

FROM

    fs_card fs

WHERE

    fs.open_id IS NOT NULL

GROUP BY fs.name having COUNT(fs.card_id)= 1

//distinct 的作用域是   所有的查询字段， 是对 该条查询结果数据 进行 去重复（比较的是结果集，即每条记录），而不是对某个字段。如果上面的名字相同的两条数据如果有查询的某个字段不同，则按照不同结果处理