2_Queries_presentation_l1_v2

Queries

Questions

What is query?
How can we make queries?
What for do we need queries?

Query

A query is a request for data or information from a database table or combination of tables. This data may be generated as results returned by Structured Query Language (SQL) or as pictorials, graphs or complex results, e.g., trend analyses from data-mining tools.

Why do we need queries?

https://www.tutorialspoint.com/ms_access/ms_access_query_data.htm
Read an article

Answer following questions:

Why do we use queries?
How does queries ease our work with database?
How do query ease working with several tables?
What is called by action queries?

Check yourself!

You can use a query to answer a simple question, to perform calculations, to combine data from different tables, or even to add, change, or delete table data.
As tables grow in size they can have hundreds of thousands of records, which makes it impossible for the user to pick out specific records from that table.
In a well-designed database, the data that you want to present by using a form or report is often located in several different tables. With queries we can easily take data from all of them.
Queries that add, change, or delete data are called action queries.

Thanks for the attention!