Select query most common query data is selected from

This preview shows page 2 - 4 out of 10 pages.

Select Query - Most common query. Data is selected from the table and displayed in the datasheet. Action Query - performs an action on the table (such as selecting data from one table and adding it to another or creating a new table). Crosstab query - performs calculations on the values in a field and then displays results in a datasheet. 12. What are three limitations associated with using flat file databases for data management? First is wasted time on entering redundant information. Second is the process is prone to errors. Third is locating every row that contains data for a change leads to a waste of time and possible inconsistent data. 13. What is a primary key? What is a foreign key? How do these keys work together in a database? A primary key is one field that creates a unique value in each record so you can identify each record in the table. A common field is a field that appears in two or more tables and contains identical data. The common field in the second table is called the foreign key. 14. Which of the following pairs of entities would require a one-to-one, one-to-many, and many-to-many relationship? Describe your answer. A. Customers and orders Many-to-many – There are many customers and they may have multiple orders. B. States and state capitals One-to-one – I chose this because there can only be one state and one capital per state. They are both unique. C. College students and classes
Image of page 2

Subscribe to view the full document.

Review Questions One-to-many – One student has many classes so this would be the correct relationship. 15. What is entity integrity? What is referential integrity? Should you enforce referential integrity in a database all the time? Why or why not? Entity integrity is a guarantee that there are no duplicate records in a table, that each record is unique, and that no primary key field contains null values. Referential integrity is a rule that if the foreign key in one table matches the primary key in a second table, the values in the foreign key must match the values in the primary key. No, you should not always enforce referential integrity for cases such as making updates to primary keys or cascading updates. 16. Name and describe the three types of anomalies that can occur in a database. Deletion anomaly – occurs when a user deletes data from a database and unintentionally deletes the only occurrence of that data in the database. Update anomaly – occurs when, due to redundant data in a database a user fails to update some records or updates records erroneously. Insertion anomaly – occurs when a user cannot add data to a database unless it is preceded by the entry of other data. 17. What is the goal of normalization? Name and describe the three normal forms. 1NF – A table is in 1NF if it does not contain any repeating groups.
Image of page 3
Image of page 4
  • Fall '07
  • Unk
  • Relational model, Database normalization

{[ snackBarMessage ]}

Get FREE access by uploading your study materials

Upload your study materials now and get free access to over 25 million documents.

Upload now for FREE access Or pay now for instant access
Christopher Reinemann
"Before using Course Hero my grade was at 78%. By the end of the semester my grade was at 90%. I could not have done it without all the class material I found."
— Christopher R., University of Rhode Island '15, Course Hero Intern

Ask a question for free

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern