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D427 Question and answers correctly solved 2024 D427 - Data Management Relational data structure - correct answer A table has a name, a fixed tuple of columns, and varying sets of rows. A column has a name and a data type. A row is a unnamed set of values. Each corresponds to a column ...

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  • September 1, 2024
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D427 - Data Management
Relational data structure - correct answer ✔A table has a name, a fixed tuple
of columns, and varying sets of rows.


A column has a name and a data type.


A row is a unnamed set of values. Each corresponds to a column and belongs
to the columns data type.


A data type is a name set of values, from which column values are drawn.


Similar concepts in databases - correct answer ✔DATABASES
MATHEMATICS FILES
table relation file
column attribute field
row tuple record
data type domain data type


Can a query select one specific row from a table? - correct answer ✔A query
selects a specific row by specifying one or more row values. Ex:
SELECT EmployeeName FROM Employee WHERE EmployeeID = 2594;


What is the result of a relational operation? - correct answer ✔What is the
result of a relational operation?


Name some operational operations - correct answer ✔Select, Project,
Product, Join, Union, Intersect, Difference, Rename, Aggregate

,An SQL statement can implement only one relational operation. T/F - correct
answer ✔FALSE


- Most SQL queries implement several operations. Ex: SELECT Name FROM
Employee WHERE Salary > 50000; implements both a select and a project
operation.


Unique primary key is an example of a relational rule.
T/F - correct answer ✔All relational tables should have a column with a
primary key.


primary keys identify individual rows.


Delete cascade is an example of a relational rule.
T/F - correct answer ✔FALSE


-Delete cascade is a business rule, not a relational rule. The delete cascade
rule requires that, when a row of a particular table is deleted, all related rows
are also deleted. Deleting related rows depends on business policy, and may
apply to some tables but not others.


Data in a relational database can violate relational rules.
T/F - correct answer ✔True


-Depending on how tables are specified, some relational rules can be violated.
Ex: A table with no primary key can be created. However, rule violations often
create business problems and should normally be avoided or automatically
prevented.

, All tables must have a primary key with no repeated values.
R or B rule - correct answer ✔Relational rule


All rows in a particular column must have known values.
R or B rule - correct answer ✔Business rule


Different columns of the same table must have different names. R or B rule -
correct answer ✔Relational rule


A database designer and database user both use SQL.
T/F - correct answer ✔True


-Designers use SQL to create the database and tables


-The users uses SQL to insert, retrieve, update, and delete from the tables.


All database systems use identical SQL statements
T/F - correct answer ✔FALSE


- SQL implementations differs in small ways between databases.


- correct answer ✔Literals - Explicit values that are string, numeric, or binary
.Strings must be surrounded by single quotes or double quotes.Binary values
are represented with x'0' where the 0 is any hex value .


Ex: 'String' "String" 123 x'0fa2'

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