Kinh Nghiệm Hướng dẫn There is a greater impact of failure in a nondatabase, file-oriented system. 2022
Lê Minh Châu đang tìm kiếm từ khóa There is a greater impact of failure in a nondatabase, file-oriented system. được Cập Nhật vào lúc : 2022-12-24 08:22:04 . Với phương châm chia sẻ Mẹo Hướng dẫn trong nội dung bài viết một cách Chi Tiết 2022. Nếu sau khi tham khảo tài liệu vẫn ko hiểu thì hoàn toàn có thể lại Comment ở cuối bài để Ad lý giải và hướng dẫn lại nha.Traditional File Oriented Approach
Nội dung chính Show- Uploaded byDocument InformationOriginal TitleAvailable FormatsShare this documentShare or Embed DocumentSharing OptionsDid you find this document useful?Is this content inappropriate?Original Title:Uploaded byReward Your CuriosityShare this documentShare or Embed DocumentSharing OptionsQuick navigationWhich of the following is a problem that Data redundancy causes?What is data dependence and why is it lacking in file system?Which of the following is considered to be a disadvantage of a DBMS?What are the two major weakness of file processing systems?
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Redundancy wastes space because you are storing different types of data in the same place. False When you need to change data, redundancy makes your changes more cumbersome and time-consuming. True An entity is also defined as an attribute. Flase An entity is a person, place, object, sự kiện, or idea for which you want to store and process data. Each entity has its own table. The attributes of an entity become the columns in the table. An attribute is a characteristic or property of an entity. An attribute is a characteristic or property of an entity. True Attributes describe and provide details about entities An attribute is known as a row in most databases. False. Rows are commonly known as records, which provide all information about the entity. A database will not only hold information about multiple types of entities, but also information about the relationships among these multiple entities. True, which is why there is a difference between relational and non-relational database Each table in a database represents two or more entities. False Each entity has its own table. The relationship between different entities (in different tables) is handled by their common columns. True. This is why keys become important in defining relationships between tables Software packages, called database management systems, can do the job of manipulating databases for you. True. Programs created with Visual Basic, Java, Perl, PHP, or C++ can access the database directly, rather than having to access it through the DBMS. False Many advanced text editors and IDEs have plug-ins that allow developers to access database. To create forms to use with a database you must write a program. Flase There must be a way for user to interact with the DBMS. This can done using languages like: Java, Python, JavaScript, and PHP. Sharing data is one advantage of database processing. True - Data sharing leads to larger pools of data that can be collected and maintained. An advantage of using the database approach to processing is that it facilitates Consistency. True The database approach to processing offers nine clear advantages (PG 13) A DBA can assign passwords to prevent unauthorized users from accessing the data. True A DBA can manage users and create policies There is a greater impact of failure in a nondatabase, file-oriented system. False //Page 16 In a nondatabase, file-oriented system, each user has a completely separate system; the failure of any single user’s system does not necessarily affect any other user. On the other hand, if several users are sharing the same database, a failure for any one user that damages the database in some way might affect all the other users. Storing the same data in more than one place is called ____. Redundancy A(n) ____ is also called a field or column in many database systems. Attribute . A(n) ____ is a person, place, object, sự kiện, or idea for which you want to store and process data. Entity A(n) ____ is the computer counterpart to an ordinary paper file you might keep in a file cabinet or an accounting ledger. Record The ____ of an entity become the columns in the database table. Attribute Unlike a typical data file, a database can store information about multiple ____. Entities A visual way to represent a database is with a(n) ____. View Popular ____ include Access, Oracle, DB2, MySQL, and SQL Server. Relational Databases During the ____ process, a database expert determines the structure of the required database. Database Design ____ are screen objects used to maintain, view, and print data from a database. Forms . An integrity constraint is a rule that ____. data must follow in the database A database has ____ if the data in it satisfies all established integrity constraints. Integrity ____ is the prevention of unauthorized access to the database. Security A(n) ____ frees programmers who write database access programs from having to engage in mundane data manipulation activities, such as adding new data and deleting existing data. DBMS A person who is in charge of a database within an organization is often called the database ___ Database Admin A good ____ should provide an opportunity for users to incorporate integrity constraints when they design the database. DBA A DBMS lets you assign users to ____. DBMS lets you assign users to groups ____ is a property that lets you change the structure of the database without requiring you to change the programs that access the database. Data Independence One disadvantage of a database system is Larger file size Increased complexity Greater impact of failure More difficult recovery In a(n) ____________________ relationship between two entities, each occurrence of the first entity is related to many occurrences of the second entity and each occurrence of the second entity is related to only one occurrence of the first entity. One to many A program, or collection of programs, through which users interact with a database is known as a(n) _ DBMS In an E-R diagram, ____________________ represent entities. rectangles represent entities In an E-R diagram, ____________________ represent relationships between connected entities. Line In an E-R diagram, the ____________________ the end of a line indicates the “many” part of the one-to-many relationship between two entities. Line with a dot the end A group of people in charge of a database within an organization is often called the ____________________. DBAs The problem of inconsistency in data is a direct result of redundancy and not providing integrity constraints Eliminating ____________________ not only saves space but also makes the process of updating data much simpler. redundancy A good _________________________ has many features that allow users to gain access to data in a database without having to do any programming. DBMS A database file requires a large amount of disk space and internal __________ memory A relational database handles entities, attributes, and relationships by storing each entity in its own table. True Each entity is stored in its own table. (PG31) The attributes of an entity become the fields or columns in a table True The attributes of an entity become the fields or columns in the table Each column in a table should have a unique name, and entries in each column should all “match” this column name. True Each column in a table should have a unique name, and all entries in each column should be consistent with this column name In a relation, the order of the columns is important. The order in which columns and rows appear in a table should be immaterial. In a relation, the order of rows is important. In addition, each row should be unique. After all, when two rows in a table contain identical data, the second row does not provide any information that you do not already have. In addition, for maximum flexibility, the order in which columns and rows appear in a table should be immaterial (unimportant under the circumstances; irrelevant.). A relational database is a collection of relations. True An unnormalized relation is a table that has more than one row. False some of the entries contain repeating groups and, thus, are not single-valued. Such a structure is called an unnormalized relation. A column whose value uniquely identifies a given row in the table is the secondary key. False, that would be the primary key A query is a question represented in a way that the DBMS can recognize and process. True QBE is a visual approach to writing queries. true Query-By-Example (QBE) An approach to writing queries that is very visual. With QBE, users ask their questions by entering column names and other criteria using an on-screen grid, and data appears on the screen in tabular form. (PG33) Access automatically adds double quotation marks around values in the design grid that are formatted as Short Text fields when you run the query or move the insertion point to another cell in the design grid. true Access automatically adds double quotation marks around the value when you run the query or move the insertion point to another box in the design grid. (PG 37) The comparison operators are +, *, %, and /. False <, >, =, != The comparison operators are also known as relational operators. true comparison operator, also called a relational operator (PG 37) In an AND criterion, the overall criterion is true if either of the individual criteria is true. False T&T = T, T&F=F, F&T=F, F&F=F The concept of grouping means that statistics will be calculated for individual records. True, functions in combination with grouping, where calculations affect groups of records. Grouping simply means creating groups of records that share some common characteristic. A relation is a(n) ____. Association between entities Based on the statement below, which of the following is the primary key? Rep (RepNum, LastName, FirstName, Street, City, State, PostalCode Commission, Rate) RepNum, it is the first listed attribute When duplicate column names exist in a database and you need to indicate the column to which you are referring, Ture, which is called qualifying the field Rows are also called Records (Death Row Records) The ____ key of a table is the column or collection of columns that uniquely identifies a given row in that table. Primary Key The compound criteria (conditions) are created by using ____. AND, OR Count, Sum, Avg, Max, and Min are a few of the built-in statistics or ____ functions that can be used in a query. Aggregate Function If you are sorting records by more than one field, the more important field is called the ____. Major sort key The other is the minor sort key A query that changes data is a(n) ____ query. UPDATE A ____ query creates a new table using the query results. CREATE TABLE SQL uses commands to create tables, update tables, and retrieve data from tables. True You can use the SQL CREATE TABLE command to insert rows into a table. False You use INSERT statement A valid name for a table might be tbl$Student. False Some common restrictions placed on table and column names by DBMSs are as follows CHAR data types are numbers without a decimal part. False Fields will appear in the query results in the order in which they are listed in the SELECT clause. True In a SELECT statement, the WHERE clause is mandatory. False Instead of listing all the field names in the SELECT clause, you can use the @ symbol. False A simple condition includes the field name, a comparison operator, and either another field name or a value. True There are two versions of the “not equal to” operator: <> and !=. True Notice that there are two versions of the “not equal to” operator: < > and !¼. When you connect simple conditions using the AND operator, all the simple conditions must be false for the compound condition to be true. False Preceding a condition by the NOT operator reverses the truth or falsity of the original condition. True The BETWEEN operator is an essential feature of SQL. False You can combine values in character fields. True The IN operator provides a concise way of phrasing certain conditions. True There is no difference between the COUNT function and the SUM function. False You can use the GROUP BY clause and the ORDER BY clause in the same SELECT Statement. True The HAVING clause is to groups what the WHERE clause is to rows. True When rows are grouped, one line of output is produced for each group. True A WHERE and a HAVING clause cannot be included in the same query. False For each pair of tables to be joined, a condition must be included indicating how the tables are related. True When you use a name containing a space in Access SQL, you must ____. enclose it in square brackets Many versions of SQL require you to end a command with a ____. Semicolon The basic form of an SQL retrieval command is ____. SELECT-FROM-WHERE When used after the word SELECT, the ____ symbol indicates that you want to include all fields in the query results in the order in which you described them to the DBMS when you created the table. * To use a wildcard, include the ____ operator in the WHERE clause. Like . In versions of SQL other than Access, the ____ is used as a wildcard to represent any collection of characters. percent sign ( % ) In Access SQL, the ____ is used as a wildcard to represent any individual character. question mark (?) The ____ function calculates the number of entries in a table. Count when a subquery is used, ____ is(are) evaluated first. the subquery query The ____ clause can be used to create groups of records. Group By When rows are grouped, ____. one line of output is produced for each group To make changes to existing data in a table, you would use the ____ command. Update To add new data to a table, use the ____ command. Insert You can save the results of a query as a table by including the ____ clause in the Query. INTO Based on the code above, list the number, name, credit limit, and balance for all customers with credit limits that exceed their balances. SELECT CustomerNum, CustomerName, CreditLimit, Balance FROM Customer WHERE CreditLimit>Balance ; Based on the code above, list the number, name, and balance of all customers with balances greater than or equal to $2,000 and less than or equal to $5,000. SELECT CustomerNum, CustomerName, Balance FROM Customer WHERE Balance BETWEEN 2000 AND 5000 ; Based on the code above, list the number, name, and available credit for all customers with credit limits that exceed their balances. SELECT CustomerNum, CustomerName, CreditLimit-Balance AS AvailableCredit FROM Customer WHERE CreditLimit>Balance ; Based on the code above, list the number, name, and complete address of every customer located on a street that contains the letters “Oxford”. SELECT CustomerNum, CustomerName, Street, City, State, PostalCode FROM Customer WHERE Street LIKE "%Oxford%" ; Based on the code above, list the number, name, street, and credit limit of all customers. Order the customers by name within descending credit limit. SELECT CustomerNum, CustomerName, Street, CreditLimit FROM Customer ORDER BY CreditLimit DESC, CustomerName ; Based on the code above, for each sales rep, list the rep number, the number of customers assigned to the rep, and the average balance of the rep’s customers. Group the records by rep number and order the records by rep number. SELECT RepNum, COUNT(*), AVG(Balance) FROM Customer GROUP BY RepNum ORDER BY RepNum ; Based on the code above, list the number and name of all customers that are either represented by sales rep 30 or that currently have orders on file, or both. SELECT CustomerNum, CustomerName, FROM Customer WHERE RepNum='30' UNION SELECT Customer.CustomerNum, CustomerName, FROM Customer, Orders WHERE Customer.CustomerNum=Orders.CustomerNum ; Based on the code above, list the descriptions of all items that are located in Storehouse3 and for which there are more than 20 units on hand. SELECT Description FROM Item WHERE Storehouse="3" AND OnHand>20 ; Based on the code above, list the descriptions of all items that are located in Storehouse 3 or for which there are more than 20 units on hand, or both. SELECT Description FROM Item WHERE Storehouse="3" OR OnHand>20 ; Based on the code above, list the descriptions of all items that are not in Storehouse 3. Based on the code above, list the descriptions of all items that are not in Storehouse SELECT Description FROM Item WHERE NOT Storehouse="3" ; Based on the code above, find how many items are in category TOY. SELECT COUNT(*) FROM Item WHERE Category='TOY' ; Based on the code above, list the complete student table. SELECT * FROM Student ; Based on the code above, list the name of every student whose postal code is 10113. SELECT FirstName, LastName FROM Student WHERE PostalCode="10113" ; Based on the code above, find the name of the student whose ID is 1167. SELECT FirstName, LastName FROM Student WHERE StudentID='1167' ; Based on the code above, change the postal code of the student with ID 11433 to 14455. UPDATE Student SET PostalCode="14455" WHERE StudentID='11433' ; Based on the code above, delete any row in the OrderLine table in which the item number is MT03. DELETE FROM OrderLine WHERE ItemNum='MT03' ; Views cannot be used to examine table data. False. An individual can use a view to create reports, charts, and other objects that show database data. True. A view is a physical table in the DBMS. False To create a view in Access, you simply create and then save a query. True One advantage of using views is that they provide data dependence. False. One advantage of a view is that different users can view the same data in different ways. True Indexes can increase the efficiency with which data is retrieved from the database. True When you create an index whose key has a single field, you have created what is called a single-column index. True The command DEL INDEX CustList; would remove the index named CustList. False. The SQL command used to drop (delete) an index that is no longer necessary is DROP INDEX, which consists of the words DROP INDEX followed by the name of the index to drop. The following command will enable Jones to retrieve data from the Customer table, but not to take any other action: GRANT SELECT ON Customer Jones ; False. The following command will enable user Jones to retrieve data from the Customer table but not take any other action.GRANT SELECT ON Customer TO Jones Referential integrity is specified using the FOREIGN KEY clause in the SELECT command. False Legal-values integrity is the property that states that no record can exist in the database with a value in the field other than one of the legal values. True Information about tables in the database is kept in the system catalog. True A stored procedure is placed on a client computer. False Access supports stored procedures. False The ____ command will create an application program's or individual user's picture of the database. CREATE VIEW A row-and-column subset ____ consists of a subset of the rows and columns in some individual table. View??? To create an index named RepBal with the keys RepNum and Balance and with the balances listed in descending order, the command is ____. CREATE INDEX RepBal ON Customer (RepNum, Balance DESC) ; ??? The ____ statement will take away user privileges to the database. REVOKE In Access, a key symbol appears in the row selector of the field that is the ____ key. Primary To create the primary key clause for the Customer table on the CustomerNum field, the correct statement is ____. PRIMARY KEY (CustomerNum) To create the primary key clause for the OrderLine table on the OrderNum and ItemNum fields, the correct statement is ____. PRIMARY KEY (OrderNum, ItemNum) Essentially, setting the value in a given field to ____ is similar to not entering a value in it all. Null Which of the following statement fragments will only allow a CreditLimit of $5,000, $7,500, or $15,000? CHECK (CreditLimit IN (5000, 7500, 15000)) The CHECK clause can be included in the ____ command. ALTER TABLE In SQL, you use the CHECK clause to enforce ____ integrity. Legal-values A table that is in first normal form is better than one that is in second normal form. False. 4th > 3rd > 2nd > 1st To correct update anomalies in a database, tables must be converted into various types of normal forms. True. If B is functionally dependent on A, you can also say that B functionally determines A. True Functional dependencies can be determined by looking sample data. False Removal of repeating groups is the starting point in the quest to create tables that are as không lấy phí of problems as possible. True In general, when converting a non-first normal form table to first normal form, the primary key will usually include the original primary key concatenated with the key to the repeating group. True A table that is in first normal form may contain problems that will require you to restructure it. True If the primary key of a table contains only a single column, the table is automatically in first normal form. False In a dependency diagram, the arrows below the boxes indicate the normal dependencies. False Tables that are in second normal form do not contain problems. False The most recent definition of third normal form is referred to as the Boyce-Codd normal form. True . The primary key in a table will be a determinant. True Converting to third normal form always avoids the problems related to dependencies. False The normalization process used to convert a relation or collection of relations to an equivalent collection of third normal form tables is a crucial part of the database design process. True By splitting relations to achieve third normal form tables, you create the need to express interrelation constraints. True Potential problems in the design of a relational database are known as ____. Update anomalies. The fact that column B is functionally dependent on column A can be written as ____ A → B. If B (an attribute) is functionally dependent on A, we can also say that ____. A functionally determines B. The ____ is a column (or collection of columns) A such that all other columns are functionally dependent on A and no subcollection of the columns in A has this property. Primary Key. The definition for ____ also defines a candidate key. Primary Key. A(n) ____ is a column or collection of columns on which all columns in the table are functionally dependent. Candidate key. An alternate key is a ____ Column that could be a primary key but was not chosen. A table is in first normal form if it does not contain ____. Repeating groups. A table that contains a repeating group is called a(n) ____. Unnormalized relation. If there is more than one possible choice for the primary key, and one of the possibilities is chosen to be the primary key, the others are referred to as ____. Alternate keys. From all the ____ keys, one is chosen to be the primary key. Candidate. Which of the following contains a repeating group? Orders (OrderNum, OrderDate, (ItemNum, NumOrdered) ) Orders (OrderNum, ItemNum, NumOrdered ) Orders (OrderNum, OrderDate) Orders (OrderNum, OrderDate, ItemNum, NumOrdered ) Orders (OrderNum, OrderDate, (ItemNum, NumOrdered) ) A column is a nonkey column if it is ____. Not a part of the primary key. Another name for a nonkey column is a ____. Nonkey attribute. 30. Second normal form can be defined as a table that is in first normal form but that contains no ____. Partial dependencies. The information-level design methodology involves representing the individual user view as a collection of tables, refining them to eliminate any problems, and then merging them into a cumulative design. True A design that supports all user views is called a constructive design. False The second step in creating a user view is to represent the user view as a collection of tables. False The first step in creating a user view is to normalize the tables. False When provided with a user view or some sort of stated requirement, you must develop a collection of tables that will support it. True The primary key is a unique identifier. True The basic relationships among entities are: one-to-many, many-to-many, and one-to one. True. In a one-to-many relationship, the primary key of the “many” table becomes the foreign key of the “one” table. False Careful planning in the early stages of the normalization process will usually avoid the need to consider fourth normal form. True You create a many-to-many relationship by creating a new table whose primary key is the combination of the primary keys of the original tables. True There are two types of primary keys that you can use in your database design. False A foreign key is a column or collection of columns in one table that is required to match the value of the primary key for some row in another table, or be null. True In DBDL, you represent a table by listing all columns and then underlining the primary key. True In an entity-relationship diagram, rectangles represent foreign keys. False When you use an E-R diagram to represent a database, it visually illustrates all the information listed in the DBDL. True In an E-R diagram, a dashed line represents an identifying relationship and a solid line represents a nonidentifying relationship. False. Nulls are used when a value is either unknown or inapplicable. True. When you combine third normal form tables, the result will always be in third normal form. False. The use of an “m” and an “n” in an E-R diagram indicates a many-to-many relationship. True A weak entity is a column or collection of columns that could have been chosen as a primary key, but was not. False A set of requirements that is necessary to support the operations of a particular database user is known as a(n) ____. User View. he properties of the entities you choose as you design the user view will become the ____ in the appropriate tables. Columns If each employee works in a single department and each department has only one employee, the relationship between employees and departments is ____. One-to-one A(n) ____ is a primary key that consists of a column that uniquely identifies an entity, such as a person’s Social Security number. Natural Key? A column that you create for an entity to serve solely as the primary key and that is visible to users is called a(n) ____. Artificial Key.Which of the following is a problem that Data redundancy causes?
Data redundancy occurs when the same piece of data exists in multiple places, whereas data inconsistency is when the same data exists in different formats in multiple tables. Unfortunately, data redundancy can cause data inconsistency, which can provide a company with unreliable and/or meaningless information.What is data dependence and why is it lacking in file system?
Dataindependenceexists when changes in the data characteristics don't require changes in theprograms that access those data. File systems lack data independence because all data accessprograms are subject to change when any of the file system's data storage characteristics – such aschanging a data type -- change.Which of the following is considered to be a disadvantage of a DBMS?
Cost of Hardware and Software – This is the first disadvantage of the database management system. This is because, for DBMS, it is mandatory to have a high-speed processor and also a large memory size. After all, nowadays there is a large amount of data in every field which needs to be store safely and with security.What are the two major weakness of file processing systems?
The file processing system has the following major disadvantages: Data redundancy and inconsistency. Tải thêm tài liệu liên quan đến nội dung bài viết There is a greater impact of failure in a nondatabase, file-oriented system.