Quiz 12: Managing and Sharing a Database
• Filters are conditions that can be applied on Access forms or datasheets or tables displayed using Access, using these conditions user can view or access only required amount of data from the datasheet. • For example a datasheet contains information about all its customers, but user wants to view the list of customers who are of age above 35, in such situations, a condition or a filter is specified on the Age field of the customer, so that only the customer records whose age is above 35 are displayed. • There are many types of filters that can be used to filter records in a data sheet, one of them is Filter By Form which filters records based on multiple conditions and uses the same comparison operators used in a query. The comparison operators used by queries are ' ',' ',' '.
• Filters are conditions that can be applied on Access forms or datasheets or tables displayed using Access, using these conditions user can view or access only required amount of data from the datasheet. • The users can save a filter as a Query using the advanced tools available in the design layout, such that the user can reuse the filter condition on the form or datasheet by opening the saved queries or objects.
A Sub Query is an Inner query, similar to SQL queries provided by oracle, Access also provides Sub Queries. That is, in a SQL Select query, another Select query is embedded. The second query or the inner query is called as a sub query. • Sub queries are executed first, the outer query is always evaluated basing on the result of the subquery or inner query. • For example: user wants to retrieve customers information who are working in department sales. Select customer_id, customer_name from tblcustomer where dept_id = ( Select dept_id from tbldepartment where dept_name='sales'); So here the sub query or inner query "Select dept_id from tbldepartment where dept_name='sales' "is executed first, if suppose the inner query results is one record, that record is used to evaluate the outer query.