The helpful significance of taking the logical see of a database is the it serves together a reminder that the simple record concept of data storage.
You can think of a table as a persistent representation of a reasonable relation.
Because the relational design uses attribute worths to establish relationships among tables, countless database users effectively assume that the term relation describes such relationships.
The stimulate of the rows and also columns is essential to the DBMS.
Numeric data space data on which you can perform meaningful arithmetic procedures.
Character data deserve to contain any type of character or symbol intended because that mathematical manipulation.
Each table in a relational database must have actually a main key.
A proper understanding the the concept and use of secrets in a relational database version is very important.
If A identify B, C, and also D, you create A = B, C, D.
Only a single attribute, not multiple attributes, specifies functional dependence.
If the attribute (B) is functionally dependency on a composite vital (A) however not on any type of subset of the composite key, the attribute (B) is fully functionally dependence on (A).
A null is produced when you push the Enter vital or the Tab an essential to relocate to the following entry without making a prior entry of any kind of kind.
There is never ever a great reason to use null worths in a database.
Depending top top the sophistication of the application development software, nulls can develop problems when features such together COUNT, AVERAGE, and SUM space used.
Tables within a database share common characteristics that permit the tables come be linked together.
A foreign vital must exist in both tables that have actually a relationship.
All RDBMSs enforce integrity rules automatically.
Referential and entity integrity space two names because that the same thing.
Tables must have the exact same attribute characteristics (the columns and also domains must be identical) to be provided in a UNION.
The difference operator subtracts one table indigenous the other.
The pick operator returns a vertical subset the a table.
In a natural join, the pillar on which the join was made occurs twice in the new table.
A left outer sign up with on tables CUSTOMER and also AGENT yields all of the rows in the client table, including those that do not have a corresponding value in the certified dealer table.
The divide operation supplies one single-column table (i.e. Shaft \"a\") together the divisor and also one two-column table (i.e. Columns \"a\" and also \"b\") as the dividend.
A data dictionary includes metadata—data about data.
A data thesaurus is sometimes explained as \"the database designer’s database\" because it records the design decisions around tables and their structures.
Current relational database software generally provides only a system magazine (and no a data dictionary).
The one-to-many (1:M) connection is conveniently implemented in the relational model by placing the foreign an essential of the \"1\" side in the table the the \"many\" side together a main key.
As rare as 1:1 relationships need to be, particular conditions absolutely call for their use.
DBMSs usage indexes for countless different purposes.
____ logic, used extensively in mathematics, gives a framework in i beg your pardon an delinquent (statement of fact) have the right to be proved as either true or false. A. Property b. Database c. Relational d. Index
The relational database model enables you to view data ____ rather than ____. A. Relationally, hierarchically b. Hierarchically, relationally c. Physically, logically d. Logically, physically
d. Logically, physically
The relational model’s creator, E. F. Codd, provided the term relation as a synonym for ____. A. Index b. Key c. Table d. Reationship
A(n) ____ is perceived as a two-dimensional structure composed the rows and columns. A. Table b. Rowset c. Attribute d. Intersection
Date qualities contain calendar dates stored in a special format known together the ____ day format. A. Epoch b. Calendar c. Julian d. Logical
____ data have the right to have just a true or false (yes or no) condition. A. Reasonable b. Character c. Day d. Numeric
In the relational model, ____ are important due to the fact that they are used to ensure the each row in a table is unique identifiable. A. Connections b. Secrets c. Indexes d. Reasonable structures
In the context of a database table, the declare \"A ____ B\" suggests that if you understand the value of attribute A, you can look up the value of attribute B. A. Consists of b. Is pertained to c. Owns d. Determines
The attribute B is ____ the attribute A if each value in tower A identify one and only one value in pillar B. A. Logically dependency on b. Owned by c. Figured out by d. Functionally dependence on
d. Functionally dependence on
Any attribute the is part of a vital is recognized as a ____. A. Vital attribute b. Logical attribute c. Vital determiner d. Selector
a. Vital attribute
If the attribute (B) is functionally dependency on a composite an essential (A) however not on any subset of the ____ key, the attribute (B) is totally functionally dependence on (A). A. Foreign b. Distinctive c. Composite d. Complete
A ____ is any an essential that unique identifies every row. A. Superkey b. One-of-a-kind c. Selective d. Candidate
No data entrance at all is recognized as a(n) ____. A. Nil b. Null c. North d. Zero
Controlled ____ renders a relational database work. A. Connections b. Logic c. Chaos d. Redundancy
A ____ is a textual depiction of the database tables wherein each table is provided by its name complied with by the list of its attributes in parentheses. A. Relational dictionary b. Reasonable schema c. Relational schema d. Data dictionary
c. Relational schema
In the adhering to 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 an essential contains a value, that value refers to an existing precious tuple (row) in an additional relation. A. Truth b. Uniqueness c. Direction d. Relations
A ____ crucial is characterized as a vital that is supplied strictly because that data retrieval purposes. A. Lookup b. International c. Candidate d. Secondary
A ____ key is a minimal (irreducible) superkey. A. An additional b. Candidate c. Primary d. Foreign
All primary key entries room unique, and no part of a primary vital may be ____. A. Zero b. A foreign crucial c. Null d. A candidate key
A client table’s primary an essential is CUS_CODE. The client primary key column has no null entries, and also all entries space unique. This is an example of ____ integrity. A. Reality b. Referential c. Complete d. Null
The ____ constraint can be placed on a shaft to ensure that every heat in the table has a value for the column. A. Has VALUE b. Not NULL c. MUST have actually VALUE d. No EMPTY
b. Not NUL
To be considered minimally relational, the DBMS should support the an essential relational operators ____, PROJECT, and JOIN. A. Intersect b. UNION c. Distinction d. SELECT
____ combines every rows from two tables, excluding duplicate rows. A. Crossing b. UNION c. Difference d. SELECT
____ yields only the rows that show up in both tables. A. Crossing b. UNION c. Difference d. SELECT
____, likewise known as RESTRICT, yields values for all rows found in a table that fulfill a given condition. A. Crossing b. UNION c. Distinction d. SELECT
____ yields a upright subset the a table. A. Task b. Choose c. UNION d. DIFFERENCE
A(n) ____ join links tables by picking only the rows with common values in their common attribute(s). A. Equal b. Unique c. International d. Natural
The equijoin bring away its name from the comparison operator ____ used in the condition. A. * b. c. = d. >
In an external join, the suitable pairs would certainly be retained and also any unequaled values in the various other table would certainly be left ____. A. In one more table b. Null c. Out of the results d. With matching values native the original table
A ____ contains at least every one of the attribute names and characteristics for each table in the system. A. Data thesaurus b. Relational schema c. Reasonable schema d. Join
a. Data dictionary
The ____ is in reality a system-created database who tables store the user/designer-created database characteristics and contents. A. Meta dictionary b. Schema c. Data thesaurus d. Device catalog
d. System catalog
In a database context, words ____ suggests the use of the very same attribute surname to label various attributes. A. Redundancy b. Homonym c. Duplicate d. Synonym
In a database context, a(n) ____ shows the usage of various names to explain the very same attribute. A. Entity 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 must be rarely in any relational database design. A. 1:1 b. 1:M c. M:1 d. M:N
Since that is offered to attach the tables that originally were connected in a M:N relationship, the composite entity framework includes—as international keys—at the very least the ____ secrets of the tables that are to it is in linked. A. Composite b. At sight c. Major d. Unique
A(n) ____ is an ordered plan of keys and also pointers. A. Table b. Superkey c. Partnership d. Index
When you define a table’s primary key, the DBMS automatically creates a(n) ____ index on the primary vital column(s) girlfriend declared. A. Key b. Incomplete c. Distinct d. Primary
Codd’s dominion of ____ states: application programs and ad hoc framework are logically unaffected when changes are made to the table frameworks that preserve the original table worths (changing bespeak of obelisk or inserting columns). A. Nonsubversion b. Logical Data freedom c. Substantial Data Sublanguage d. Verity Independence
b. Logical Data Independence
The logical see of the relational database is promoted by the development of data relationships based upon a reasonable construct recognized as a(n) ____________________.
In the relational model, ____________________ space important due to the fact that they are used to ensure that each heat in a table is uniquely identifiable.
Attribute A identify attribute B (that is, B is functionally ____________________ ~ above A) if all of the rows in the table that agree in value for attribute A also agree in value for attribute B.
A(n) ____________________ crucial can be defined as a superkey without unnecessary attributes.
If the foreign an essential contains either matching values or nulls, the table that renders use of that foreign an essential is said to exhibit ____________________ integrity
The following example exhibits ____________________ integrity: The customer table’s primary crucial is CUS_CODE. The customer primary crucial column has actually no null entries, and also all entries space unique. Similarly, the agent table’s primary vital is AGENT_CODE, and this primary key column likewise is complimentary of null entries.
To prevent nulls, some designers use special codes, recognized as ____________________, to suggest the absence of some value.
The relational operators have the home of ____________________; the is, the usage of relational algebra operator on present tables (relations) produces brand-new relations.
PRODUCT returns all feasible pairs the rows from 2 tables—also known as the ____________________ product.
____________________ is the genuine power behind the relational database, permitting the usage of elevation tables linked by common attributes.
A(n) ____________________ web links tables on the communication of one equality problem that compares stated columns of every table.
____________________ joins room especially helpful when you space trying to recognize what value(s) in related tables cause(s) referential truth problems.
A(n) ____________________ offers a detailed description of all tables discovered within the user/designer-created database.
The ____________________ magazine can be defined as a detailed system data dictionary that defines all objects within the database, consisting of data around table names, the table’s creator and also creation date, the variety of columns in every table, the data kind corresponding to each column, index filenames, index creators, authorized users, and accessibility privileges.
The ____________________ partnership is the relational database norm.
If one department chair—a professor—can chair just one department and one department deserve to have only one department chair, then the reality PROFESSOR and also DEPARTMENT exhibit a(n) ____________________ relationship.
____________________ relationships can be implemented by creating a brand-new entity in 1:M relationships through the initial entities.
Fortunately, the problems inherent in the ____________________ partnership can easily be avoided by creating a composite entity.
The appropriate use that ____________________ secrets is vital to regulating data redundancy.
Proper data ____________________ architecture requires closely defined and controlled data redundancies to function properly.
A(n) ____________________ is an orderly plan used to logically access rows in a table.
A(n) ____________________ index is an table of contents in which the index an essential can have only one tip value (row) linked with it.
The index vital can have actually multiple attributes, this is called a(n) ____________________ index.
Codd’s dominance of ____________________ states that every value in a table is guarantee to be obtainable through a mix of table name, primary key value, and also column name.