Criteria in a query

[Khalil Handal]

A familyName field in a query has the following criteria. Can any one explain it to me please?

In (SELECT [FamilyName] FROM [tblStudents] As Tmp


GROUP BY [FamilyName],[GrandFatherName],[FathersName]
HAVING Count(*)>1 And [GrandFatherName] = [tblStudents].[GrandFatherName] And [FathersName] = [tblStudents].[FathersName])

Thanks
Khalil

[ranman256]

this IN subquery is the only way to create a DELETE query to remove records listed in another table. (FIND duplicates use it too)
It says to pull items from the sub query that match the main query field.

The IN clause is not really needed for any other queries. You can just join other tables in all other queries.
Is this from a delete query.

[Khalil Handal]

this IN subquery is the only way to create a DELETE query to remove records listed in another table. (FIND duplicates use it too)
It says to pull items from the sub query that match the main query field.

The IN clause is not really needed for any other queries. You can just join other tables in all other queries.
Is this from a delete query.

"This query is used to find siblings based on the idea that brothers and sisters have thw same father, grand father and family name. If this criteria is ommited the number of records increases from 191 to 359 records."