SQL

Question 1

Catalog

Answer 1

A named collection of schemas in an SQL environnement

Question 2

INFORMATION_SCHEMA

Answer 2

Special schema always contained in a catalog and which provides information on all schemas in the catalog and all the elements descriptors in these schemas

Question 3

Basic data types

Answer 3

• Numeric
• Boolean
• Character-string
• Bit-string
• Date and time

Question 4

Additional data types

Answer 4

• Timestamp
• Interval

Question 5

Domain

Answer 5

Name used with the attribute specification.
Makes it easier to change the data type for a domain that is used by numerous attributes

Question 6

Type

Answer 6

User defined types (UDTs) are supported for object oriented applications. Use the command CREATE TYPE

Question 7

Constraints

Answer 7

A relational model has 3 basic contraints types that are supported in SQL:
- Key constraint: a primary key value cannot be duplicated
- Entity integrity constraint: a primary key value cannot be null
- Referential integrity constraints: the foreign key must have a value that is already present as a primary key or may be null.

Question 8

Attribute constraints

Answer 8

• Basic constraints:
  
  • restrictions on attribute domain and null
  • default value of an attribute
  • not null constraints
  • check clause

Question 9

Key constraints

Answer 9

• Primary key clause: specifies one or more attributes that make up the primary key of a relation
• Unique clause: specifies alternate (secondary) keys
• Foreign key clause

Question 10

Projection attribute

Answer 10

Attributes whose values are to be retrieved

Question 11

Selection condition

Answer 11

Boolean condition that must be true for any retrieved tuple.