Modified Study questions from the mid-term for the final

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Applied Computer Science
Eugene Kaluzniacky

ACS 1803 STUDY QUESTIONS 1 THESE ARE THE SAME QUESTIONS I GAVE YOU TO PREPARE FOR THE MID- TERM TEST IN OCTOBER. BUT, FOR THE FINAL EXAM, STUDY ONLY THE QUESTIONS BELOW THAT ARE IN BOLD ( ALSO STUDY THE entire SECOND SET OF QUESTIONS ON MATERIAL AFTER THE MID TERM, THAT WILL BE UP SHORTLY) 18. What is a character, a field, a record, a file? Give examples from student data. The smallest item of data is a character: e.g., A,b,9,%,$, But storing just characters alone in a computer wont do; we need to group them. A group of characters is a field: The field has a name, a type (how the computer will represent it internally) and a length. e.g., First Name, Text type, length 15 (incl. blanks). E.g., John is an example of this field. A group of fields. side-by-side, is known as a record. A record needs to have a layout (structure, or design). e.g.: STUDNO SNAME STREET CITY MAJOR CNO CNAME GRADE Text Text Text Text Text Text Text Text 4 25 25 20 15 4 20 2 Then there is the data record itself, that is, the real world data for one record that follows this layout 1234 Lam A 491 Castle Wpg Economics 1803 Computers A A group of records that follow the same layout and that it makes sense to keep together is known as file ortable. e.g., STUDNO SNAME STREET CITY MAJOR CNO CNAME GRADE 1234 Lam A 491 Castle Wpg Economics 1803 Computers A 9876 Kelly R 22 Miller Cr Wpg Biology 2002 Finance B 4567 Ng J 399 High St Wpg Business 1304 Accounting C So, in order to store data on disk meaningfully, so that we can get a variety of useful information out, we see that we must set up our data, at least in a file. 19b.What is a relational database?. How does a database approach to storing data in a computer improve upon the flat file approach? The relational database model is the most common model used in Data Based Management Systems(DBMS). DBMS is exactly how it sounds, it's a system that is used to manage data. When purchasing this type of system it can often be called relational DBMS or just RDBMS. RDBMS is again exactly how it sounds it's a system that manages related data. In this form of a DBMS, the entities are viewed in two-dimensional tables. Rows represent the records, which is a group of fields and the columns represents the different parts to the records that are stored in the rows. Let's say you have a person's student ID number and their mailing information, there student ID number would be the row and the mailing information would be across the top in separate columns for the different information(e.g. Postal code, address, etc.). When different recordshave columns in common, different tables can be joined together. Now the RDBMS in actuality is forming a three-dimensional model. We've already discussed the rows and columns, but in RDBMS the third dimension is a row of data that is in common with another file. This allows their to be multiple files that have one input(column) in common with each other linking them. This one column in common is called a primary key. For example the student ID number and mailing information could be related to another file that has the student ID number of those same students, but with their grades. This therefore eliminates the need to repeat their mailing information for every grade they get. This is what makes RDBMS so popular, because it can eliminate repetition of data, which can save time. 20. Explain the basics of the relational data base design. What is a data base management system (dbms)? Be able to partition data into several tables such that these tables would together make a relational database. What is a query language? What is SQL? For first part see above answer A Query is a method used to request information from a database. SQL(Structured Query language) is the most common query language for the purpose of searching a database by entering various search criteria. Ex. You might ask the for it to give you the part numbers for any inventory that stocks exceed 30. Well a query language structures that query and presents the results of the query to the user. 20b. What is a database management system (dbms)? What does it do? Give an example of
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