Terms in this set (56)
Instructs the DBMS software on what tables will be in the database, what attributes will be in the tables, which attributes will be indexed, etc.
Data Definition Language
Refers to the four basic operations that can and must be performed on data stored in any DBMS.
Insertion of new records
Deletion of existing records
Data Manipulation Language
Incorporates both DDL and DML features.
-Very heavily used in practice today.
Structured Query Language
Also just called a view.
-May consist of a subset of the columns of a single table, a subset of the rows of a single table, or both.
-May also be the join of two or more base tables.
-A mapping onto the base table(s).
-Created using the CREATE VIEW command.
Update, Insert, Delete
Three Data Manipulation Operations?
This command is used to retrieve data from a relational database
A plan for what steps to take to respond to the query.
The user types the command at a workstation and presses the Enter key. The command goes directly to the relational DBMS, which evaluates the query and processes it against the database. The result is then returned to the user at the workstation.
The program that issued the SQL SELECT command and receives the resulting relation back, must treat the rows of the relation as a list of records and process them one at a time.
Select, Project and Join
The SQL SELECT command is capable of executing relational ___, ______ and ______ operations individually or in combination.
Desired attributes, can retrieve one or more rows of a table, depending on whether the search argument is a unique or non-unique attribute
Restriction/predicate showing which row is involved, limits which rows of the table are included.
ex) > = <
The required table
ex) "from salesperson"
SQL Select Between
Allows you to specify a range of numeric values in a search
SQL Select In
Allows you to specify a list of character strings to be included in a search
SQL Select Like
Allows you to specify partial character strings in a "wildcard" sense
SQL Select Distinct
Used to eliminate duplicate rows in a query result
SQL Select Order By
Takes the results of an SQL query and orders them by one or more specified attributes
A very useful operator that counts the number of rows that satisfy a set of criteria
Smallest number of units
To find the total number of units of all products that she has sold
Forming a single group of rows and some calculations on their attribute values, many situations require such calculations to be made on several different groups of rows, you want to find out the total number of units of all products so you would do this
The limitation based on the group calculation performed with the built-in-function.
To integrate data from two or more tables
Dr. E.F. Codd
The relational model was first described in a paper by ______ in 1970
Relational database management
__________ first became commercially viable in the late 1980s.
In relational database, the basic data structure that appears to be similar to a file is a ______.
primary key, candidate key
The values of a ______ and _______ of a relation must be unique.
An _______ or combination of _______ that is a foreign key in one relation of a database must be the primary key of another relation in the database.
A _______ must have the same domain of values as the primary key from which it is derived.
One-to-many binary relationships
The Salesperson Number foreign key in the CUSTOMER relation effectively establishes the one-to-many relationship between salespersons and customers
an attribute or a group of attributes whose values are unique throughout all of the rows of the relation.
ex) a relation always has a unique ___ ___
The number of attributes involved in the primary key is always the _____ number of attributes that provide the uniqueness quality
An attribute or group of attributes that serves as the primary key of one relation and also appears in another relation (foreign key in this relation)
-Crucial in relational database, because the foreign key is the mechanism that ties relations together to represent unary, binary, and ternary relationships
Domain of Values
Foreign key attribute must have same __________ as Primary key attribute in other relation
Domain of Values
Two attributes have the same domain of values if the attributes have values of the same type.
ex) Salesperson Number in SALESPERSON and in CUSTOMER - three digit whole numbers that are the identifiers for salespersons.
To retrieve what we referred to earlier as a vertical slice of the relation
ex) the command to retrieve the number and name of each salesperson in the file might look like:
___ The Salesperson Number and Salesperson Name over the Salesperson relation
In order to retrieve all of the records with a common value in a particular (nonunique) attribute
Designed to find the name of the salesperson responsible for customer 1525
The result of a relational operation will always be a _____.
The ____ ____ in a relation must have the same domain of values
One of the two identical join columns is eliminated in the process
Representing a ________ relationship in a relational database requires adding a new column, the domain of values of which is the same as the relation's primary key.
Representing a ________ relationship in a relational database requires the creation of an additional relation.
a relationship that involves three different entity types
A ternary relationship is not the equivalent of a certain number of binary many-to-many relationships
Representing a ternary relationship in a relational database requires the creation of an .
an issue in record insertion, deletion, and update.
-an issue in all database approaches, does not necessarily involve relations in isolation, and does not only involve relations that contain redundant data.
if an attempt is made to delete the record for salesperson 361 in the salesperson relation, the system will not permit the deletion to take place because the customer relation records for customers 1525 and 1700 include salesperson number 361 as a foreign key value
if an attempt is made to delete the record for salesperson 361 in the salesperson relation and the delete rule is cascade, the salesperson record will be deleted and so too, automatically, will the records for customers 1525 and 1700 in the customer relation because they have a 361 as a foreign key value
if an attempt is made to delete the record for salesperson 361 in the salesperson relation, that record will be deleted, and the salesperson number attribute values in the records for customers 1525 and 1700 in the customer relation will be changed from 361 to null