w3d2

Question 1

iso restrictions on identifiers

Answer 1

must start with a letter
no longer than 128 characters
cannot contain spaces

Question 2

every data type is

Answer 2

either pre defined, constructed or user defined

Question 3

the name of a predefined or preconstructed data type is

Answer 3

a reserved word specified by that part of ISO/IEC 9075 that specifies the data type

Question 4

the name of a user defined data type

Answer 4

is provided in it’s definition

Question 5

predefined data type

Answer 5

datatype specified by ISO/IEC 9075 AND is provided by the SQL implementation

• predefined even when the user is allowed to provide certain parameters
• is atomic(not composed of values of other data types)

Question 6

Each table has

Answer 6

a name that is unique within the schema

a structure that is the same for each of its records

Question 7

each attribute needs as a minimum

Answer 7

a unique name within the record

a data type ( which could be the name of a domain )

Question 8

Integrity constraints

Answer 8

define valid states of sql data by constraining values in base tables

Question 9

constaint can cause DBMS to

Answer 9

reject any atempt to insert, delete, or update against the restraint

Question 10

domain

Answer 10

set of legal values, (a sophisticated data type

Question 11

when not otherwise specified

Answer 11

the domain is the set of all legal values, that are based on the data type of the attribute

Question 12

CHECK

Answer 12

further specifies the legal values of a domain

Question 13

domain constraint

Answer 13

constraint specified for a domain

- applied to all columns that are based on that domain and to all values that are cast to that domain

Question 14

CONDITION ONLY CHECKED UPON

Answer 14

an insert or update of the record within the constraint

- not checked when records referred to in the check of the domain are updated or deleted

Question 15

The domain name can and should be used

Answer 15

in place of a data type by one or more data definitions

Question 16

Domains important for

Answer 16

help us recognize if we are dealing with the same type of attribute or not
- a list of domains provides us with an idea about what types of data we have in our database
By using good domain names it’s clearer to know what your talking about it what you’re talking about

Question 17

entity integrity

Answer 17

deal with the relation of records to eachother in a table

Question 18

primary key

Answer 18

one set of attributes that uniquely defines a record

Question 19

Referential integrity

Answer 19

links a set of attributes in this record to a record key in another table

Question 20

referential integrity CASCADE

Answer 20

will delete the constrained row if the referenced row in the foreign key is deleted
will update the foreign key value if the referenced value is updated

Question 21

referential integrity SET NULL

Answer 21

will set each of the attributes in the foreign key to NULL if the referenced value is changed or it is deleted(provided the foreign key’s value is not defined as not null)

Question 22

referential integrity SET DEFAULT

Answer 22

Will set each of the attributes in the foreign key to it’s default if the referenced value is changed or it’s record is deleted (provided the foreign key attributes were defined with defaults)

Question 23

referential integrity NO ACTION

Answer 23

will not allow the updating or deleting of the referenced value (default if other not specified)

Question 24

ASSERTion

Answer 24

named constraint that may relate to the content of individual rows of a table, to the entire contents of a table, or to a state required to exist among a number of tables

• an integrity constraint that is not directly linked to a table
• similar to a CHECK but involves multiple tables
• differs from a DOMAIN in that it is not a data type
• can be automatically checked every time an INPUT, UPDATE or DELETE might violate it