SQL some any all

Review some any all usage

The userinfo table contains 100 data records, one of which is named qixuejia.

1. Some and any have the same usage (I don't know if there are other differences)

Select count (*) from userinfo
Where 'qixuejia '<> some (select userid from userinfo)

If the where condition is true, this statement returns 100.

2. All

Select count (*) from userinfo
Where 'qixuejia '<> All (select userid from userinfo)

This where statement determines whether qixuejia is not equal to all userids. No is returned.

Therefore, this statement returns 0

3. Select count (*) from userinfo
Where 'qixuejia 'in (select userid from userinfo)
Returns 100

4. Select count (*) from userinfo
Where userid = 'qixuejia'
Return 1

5. Select count (*) from userinfo
Where 'qixuejia 'not in (select userid from userinfo)

Returns 0.