The valuable significance of acquisition the logical view of a database is that it serves as a reminder that the simple record concept that data storage.
You deserve to think of a table as a persistent depiction of a logical relation.
Because the relational model uses attribute worths to create relationships among tables, numerous database users properly assume that the ax relation refers to such relationships.
The stimulate of the rows and columns is important to the DBMS.
Numeric data room data on i m sorry you have the right to perform meaningful arithmetic procedures.
Character data deserve to contain any kind of character or prize intended for mathematical manipulation.
Each table in a relational database must have actually a main key.
A proper understanding the the concept and also use of secrets in a relational database model is very important.
If A identify B, C, and also D, you write A = B, C, D.
Only a single attribute, not multiple attributes, defines functional dependence.
If the attribute (B) is functionally dependency on a composite crucial (A) however not on any subset of that composite key, the attribute (B) is fully functionally dependence on (A).
A null is created when you press the Enter an essential or the Tab crucial to move to the next entry there is no making a former entry of any kind.
There is never ever a great reason to usage null values in a database.
Depending on the sophistication the the application advancement software, nulls can develop problems when features such as COUNT, AVERAGE, and SUM are used.
Tables in ~ a database re-publishing common features that allow the tables to be connected together.
A foreign an essential must exist in both tables that have actually a relationship.
All RDBMSs enforce integrity rule automatically.
Referential and entity integrity are two names because that the same thing.
Tables must have actually the same attribute attributes (the columns and also domains have to be identical) to be used in a UNION.
The distinction operator subtracts one table from the other.
The select operator returns a upright subset that a table.
In a natural join, the obelisk on i beg your pardon the join was made occurs double in the new table.
A left outer join on tables CUSTOMER and AGENT yields all of the rows in the customer table, including those that execute not have a corresponding value in the certified dealer table.
The division operation offers one single-column table (i.e. Column "a") as the divisor and one two-column table (i.e. Columns "a" and "b") together the dividend.
A data dictionary has metadata—data around data.
A data dictionary is sometimes explained as "the database designer’s database" since it records the design decisions about tables and their structures.
Current relational database software normally provides only a system catalog (and not a data dictionary).
The one-to-many (1:M) relationship is quickly implemented in the relational design by putting the foreign vital of the "1" next in the table of the "many" side together a primary key.
As rare together 1:1 relationships have to be, particular conditions absolutely need their use.
DBMSs use indexes for plenty of different purposes.
____ logic, used extensively in mathematics, provides a framework in i beg your pardon an delinquent (statement the fact) deserve to be confirmed as either true or false. A. Property b. Database c. Relational d. Index
The relational database model allows you to view data ____ quite than ____. A. Relationally, hierarchically b. Hierarchically, relationally c. Physically, logically d. Logically, physically
d. Logically, physically
The relational model’s creator, E. F. Codd, used the term relation together a synonym for ____. A. Index b. An essential c. Table d. Reationship
A(n) ____ is viewed as a two-dimensional framework composed the rows and columns. A. Table b. Rowset c. Attribute d. Intersection
Date features contain calendar days stored in a special layout known together the ____ date format. A. Epoch b. Calendar c. Julian d. Logical
____ data have the right to have only a true or false (yes or no) condition. A. Logical b. Personality c. Date d. Numeric
In the relational model, ____ room important since they are offered to ensure that each heat in a table is unique identifiable. A. Relations b. Tricks c. Indexes d. Reasonable structures
In the context of a database table, the statement "A ____ B" indicates that if you understand the worth of attribute A, you have the right to look increase the value of attribute B. A. Consists of b. Is related to c. Own d. Determines
The attribute B is ____ the attribute A if each value in column A identify one and also only one value in pillar B. A. Logically dependent on b. Owned by c. Determined by d. Functionally dependent on
d. Functionally dependent on
Any attribute that is component of a vital is recognized as a ____. A. Crucial attribute b. Reasonable attribute c. Key determiner d. Selector
a. An essential attribute
If the attribute (B) is functionally dependent on a composite an essential (A) but not on any subset of that ____ key, the attribute (B) is completely functionally dependency on (A). A. Foreign b. Distinctive c. Composite d. Complete
A ____ is any vital that uniquely identifies each row. A. Superkey b. Unique c. Selective d. Candidate
No data entry at every is known as a(n) ____. A. Nil b. Null c. North d. Zero
Controlled ____ makes a relational database work. A. Relationships b. Logic c. Chaos d. Redundancy
A ____ is a textual representation of the database tables whereby each table is detailed by its name adhered to by the perform of its qualities in parentheses. A. Relational dictionary b. Reasonable schema c. Relational schema d. Data dictionary
c. Relational schema
In the complying with table description, ____ is the major key. PRODUCT (PROD_CODE, PROD_DESCRIPT, PROD_PRICE, PROD_ON_HAND, VEND_CODE) a. PROD_DESCRIPT b. PROD_CODE c. PROD_PRICE d. PROD_ON_HAND
Referential ____ method that if the foreign crucial contains a value, that value refers to an existing valid tuple (row) in one more relation. A. Truth b. Uniqueness c. Direction d. Relations
A ____ vital is identified as a crucial that is provided strictly for data retrieval purposes. A. Lookup b. International c. Candidate d. Secondary
A ____ crucial is a minimal (irreducible) superkey. A. Second b. Candidate c. Main d. Foreign
All primary crucial entries room unique, and also no component of a primary crucial may it is in ____. A. Zero b. A foreign an essential c. Null d. A candidate key
A client table’s primary key is CUS_CODE. The client primary crucial column has no null entries, and also all entries are unique. This is an example of ____ integrity. A. Entity b. Referential c. Complete d. Null
The ____ constraint can be placed on a shaft to ensure the every heat in the table has actually a value for the column. A. Has VALUE b. Not NULL c. MUST have actually VALUE d. Not EMPTY
b. Not NUL
To be taken into consideration minimally relational, the DBMS have to support the key relational operators ____, PROJECT, and also JOIN. A. Crossing b. UNION c. Difference d. SELECT
____ combines all rows from 2 tables, not included duplicate rows. A. Intersect b. UNION c. Distinction d. SELECT
____ yields only the rows that appear in both tables. A. Intersect b. UNION c. Distinction d. SELECT
____, also known as RESTRICT, yields values for every rows uncovered in a table that meet a given condition. A. Crossing b. UNION c. Distinction d. SELECT
____ returns a upright subset that a table. A. Project b. Select c. UNION d. DIFFERENCE
A(n) ____ sign up with links tables by selecting only the rows with usual values in their usual attribute(s). A. Same b. Distinctive c. Foreign d. Natural
The equijoin bring away its surname from the compare operator ____ provided in the condition. A. * b. c. = d. >
In an outer join, the suitable pairs would certainly be retained and any unequaled values in the other table would be left ____. A. In an additional table b. Null c. Out of the outcomes d. With corresponding values indigenous the initial table
A ____ has at least all of the attribute names and also characteristics for each table in the system. A. Data thesaurus b. Relational schema c. Logical schema d. Join
a. Data dictionary
The ____ is actually a system-created database who tables save the user/designer-created database characteristics and also contents. A. Meta dictionary b. Schema c. Data dictionary d. Device catalog
d. Device catalog
In a database context, words ____ indicates the usage of the same attribute name to label various attributes. A. Redundancy b. Homonym c. Duplicate d. Synonym
In a database context, a(n) ____ suggests the use of different names to describe the exact same attribute. A. Reality b. Duplicate c. Synonym d. Homonym
____ relational form is the "relational ideal." a. 1:1 b. 1:M c. M:1 d. M:N
The ____ relationship need to be rarely in any type of relational database design. A. 1:1 b. 1:M c. M:1 d. M:N
Since that is offered to link the tables that originally were related in a M:N relationship, the composite entity structure includes—as international keys—at the very least the ____ tricks of the tables that are to it is in linked. A. Composite b. Super c. Main d. Unique
A(n) ____ is one ordered plan of keys and pointers. A. Table b. Superkey c. Connection d. Index
When you specify a table’s major key, the DBMS immediately creates a(n) ____ index on the primary an essential column(s) girlfriend declared. A. Crucial b. Incomplete c. Distinct d. Primary
Codd’s ascendancy of ____ states: applications programs and advertisement hoc facilities are logically unaffected when transforms are made to the table frameworks that maintain the initial table values (changing order of shaft or inserting columns). A. Nonsubversion b. Reasonable Data independence c. Considerable Data Sublanguage d. Verity Independence
b. Reasonable Data Independence
The logical check out of the relational database is assisted in by the production of data relationships based upon a reasonable construct well-known as a(n) ____________________.
In the relational model, ____________________ space important due to the fact that they are supplied to ensure that each heat in a table is unique identifiable.
Attribute A identify attribute B (that is, B is functionally ____________________ on A) if all of the rows in the table that agree in worth for attribute A also agree in worth for attribute B.
A(n) ____________________ key can be explained as a superkey there is no unnecessary attributes.
If the foreign crucial contains either equivalent values or nulls, the table that provides use of that foreign vital is claimed to exhibit ____________________ integrity
The following instance exhibits ____________________ integrity: The customer table’s primary crucial is CUS_CODE. The customer primary key column has no null entries, and all entries room unique. Similarly, the certified dealer table’s primary key is AGENT_CODE, and this primary key column additionally is cost-free of null entries.
To avoid nulls, some designers use unique codes, well-known as ____________________, to indicate the absence of some value.
The relational operators have the building of ____________________; that is, the use of relational algebra operators on present tables (relations) produces brand-new relations.
PRODUCT yields all possible pairs the rows from 2 tables—also recognized as the ____________________ product.
____________________ is the actual power behind the relational database, allowing the use of independent tables linked by common attributes.
A(n) ____________________ links tables top top the communication of an equality condition that compares mentioned columns of each table.
____________________ joins room especially valuable when you space trying to identify what value(s) in related tables cause(s) referential verity problems.
A(n) ____________________ gives a detailed summary of all tables uncovered within the user/designer-created database.
The ____________________ brochure can be described as a detailed system data dictionary that describes all objects in ~ the database, including data around table names, the table’s creator and creation date, the number of columns in each table, the data form corresponding to each column, index filenames, table of contents creators, authorized users, and accessibility privileges.
The ____________________ relationship is the relational database norm.
If one room chair—a professor—can chair only one department and also one department have the right to have just one department chair, climate the entities PROFESSOR and DEPARTMENT exhibition a(n) ____________________ relationship.
____________________ relationships deserve to be imposed by creating a brand-new entity in 1:M relationships through the original entities.
Fortunately, the difficulties inherent in the ____________________ relationship can conveniently be avoided by developing a composite entity.
The appropriate use that ____________________ tricks is critical to regulating data redundancy.
Proper data ____________________ design requires carefully defined and controlled data redundancies to role properly.
A(n) ____________________ is one orderly plan used to logically access rows in a table.
A(n) ____________________ table of contents is an index in i beg your pardon the index an essential can have actually only one reminder value (row) connected with it.
The index vital can have actually multiple attributes, this is referred to as a(n) ____________________ index.
Codd’s dominance of ____________________ claims that every value in a table is guaranteed to be obtainable through a mix of table name, primary key value, and also column name.