Concept explainers
Primary Key:
A Primary Key in a
Example:
Students in Universities are assigned a unique registration number.
Therefore, in a STUDENT database table, the attribute “reg_no” acts as primary key.
Foreign Key:
Foreign Key is a column in a relational database table which provides a relation between two tables. It provides a cross reference between tables by pointing to primary key of another table.
Example:
In STUDENT database table, the attribute “reg_no” acts as primary key and in COURSE database table in which the student selects his or her course, the same “reg_no” acts as foreign key for the STUDENT table.
Many-to-One relationship:
When one record in a database table is associated with one or more records in another table, the relationship between the two tables is referred as many-to-one relationship. It is also represented as M: 1 relationship.
One-to-Many Relationship:
When one record in a database table is associated with more than one record in another table, the relationship between the two tables is referred as one-to-many relationship. It is also represented as1: M relationship. This is the opposite of many to one relationship.
One-to-One relationship:
When one record in a database table is associated with one and only one record in another table, the relationship between the two tables is referred as one-to-one relationship. It is also represented as1: 1 relationship.
ENTITY- RELATIONSHIP DIAGRAM (ERD):
Entity- Relationship Diagram is also known as ER Diagram. It is used to define the conceptual view of the database as viewed by the end user. It is used to depict the database’s main components: entities, relationships and attributes.
CROW FOOT ERD:
The Crow Foot ERD is an Entity Relationship Diagram which is used to represent the cardinalities present in the basic ER diagram. It is used to represent the relationships present between two tuples or tables present in the database.
Given database tables:
Table Name: EMPLOYEE
EMP_CODE | EMP_TITLE | EMP_LNAME | EMP_FNAME | EMP_INITIAL | EMP_DOB | STORE_CODE |
1 | Mr. | Williamson | John | W | 21-May-84 | 3 |
2 | Ms. | Ratula | Nancy | 09-Feb-89 | 2 | |
3 | Ms. | Greenboro | Lottie | R | 02-Oct-81 | 4 |
4 | Mrs. | Rumpersfro | Jennie | S | 01-Jun-71 | 5 |
5 | Mr. | Smith | Robert | L | 23-Nov-59 | 3 |
6 | Mr. | Renselear | Cary | A | 25-Dec-85 | 1 |
7 | Mr. | Ogallo | Roberto | S | 31-Jul-82 | 3 |
8 | Ms. | Johnson | Elizabeth | I | 10-Sep-88 | 1 |
9 | Mr. | Eindsmar | Jack | W | 19-Apr-55 | 2 |
10 | Mrs. | Jones | Rose | R | 06-Mar-66 | 4 |
11 | Mr. | Broderick | Tom | 21-Oct-72 | 3 | |
12 | Mr. | Washington | Alan | Y | 08-Sept-74 | 2 |
13 | Mr. | Smith | Peter | N | 25-Aug-64 | 3 |
14 | Ms. | Smith | Sherry | H | 25-May-66 | 4 |
15 | Mr. | Olenko | Howard | U | 24-May-64 | 5 |
16 | Mr. | Archialo | Barry | V | 03-Sep-60 | 5 |
17 | Ms. | Grimaldo | Jeanine | K | 12-Nov-70 | 4 |
18 | Mr. | Rosenburg | Andrew | D | 24-Jan-71 | 4 |
19 | Mr. | Rosten | Peter | F | 03-Oct-68 | 4 |
20 | Mr. | Mckee | Robert | S | 06-Mar-70 | 1 |
21 | Ms. | Baumann | Jennifer | A | 11-Dec-74 | 3 |
Table Name: STORE
STORE_CODE | STORE_NAME | STORE_YTD_SALES | REGION_CODE | EMP_CODE |
1 | Access Junction | 1003455.76 | 2 | 8 |
2 | Database Corner | 1421987.39 | 2 | 12 |
3 | Tuple Charge | 986783.22 | 1 | 7 |
4 | Attribute Alley | 944568.56 | 2 | 3 |
5 | Primary Key Point | 2930098.45 | 1 | 15 |
Trending nowThis is a popular solution!
Chapter 3 Solutions
Database Systems: Design, Implementation, & Management
- create table queries using sinplified sales table 1. Which manufacturers are located in the city of New York? Show the manufacturer's name, state, postal code, and contact person. 2. Show product information for white shoes in the 'sneakers' category that cost more than $50 and have a product description that begins with the letter "b" or "t". Show only the product name, its composition, and its list price. 3. Show the product name, description, and category for all shoes with a list price of $150 or more and in one of the following categories: sneakers, boots, or sandals. Order the output alphabetically by product name. 4. How many customers do we have with a last name starting with a 'Q' living in each city? Your query should display two columns, one named cust_num and one named city. Sort the results alphabeticaly by city. 5. Show the product name, list price, customer state (call it 'CustState'), and manufacturer state (call it 'ManState') for all products made by manufacturers in…arrow_forwardDisplay the salesperson name, product finish, and total quantity sold (label as TotSales) for each finish by each salesperson.arrow_forwardBreak the list in Figure 1-31 into tables, each with a single theme. Create ID columns as you think necessary.arrow_forward
- Examine this product table's column definitions:pid number primary keypname varchar2(50)You must display column headings as shown:Product_ID Product NameWhich SELECT statement does this? SELECT pid Product_ID, pname Product Name FROM product; SELECT pid Product_ID, pname "Product Name" FROM product; SELECT pid @Product_ID, pname @"Product Name" FROM product; SELECT pid AS Product_ID, pname AS Product Name FROM productarrow_forwardPlease produce a set of nomalized relations from the following table: INVOICE Invoice Customer Customer Customer Customer Product Phone # Style Invoice Date ID # Name Address Product Unit Product Product Invoice VAT Total Description Price ID # Quantity Totalarrow_forwardCreate a list showing only the EmployeeID, Sales, and Projected Sales sorted from highest to lowest amount for Salesarrow_forward
- Create correlated and noncorrelated subqueries and understand when to use.arrow_forwardNormalize the following form into UNF 1NF, 2NF and 3NF. Show primary keys and foreign keys for all the normalized tables (from 3NF). Employee Task Record Form EmployeelD : 587 Employee Name: Smith Department ID: D1 DeparmentName : IT Task ID Task Name Duration Supervisor ID | Supervisor Name Emp_TaskJoin_Date Designing Drawing Reporting T1 70hrs S1 Khalfan 12/12/2019 T2 56hrs S2 Fatma 01/10/2020 T3 60hrs S3 Haitham 11/11/2020arrow_forwardTo create a student table with the student id, class, section, gender, name, dob, and marks as attributes where the student id is the primary key.arrow_forward
- Display the CID, CName, RID and RType from both tables using the NATURAL JOIN clause.arrow_forwardTo be more specific, what are the criteria for the page table?arrow_forwardBased on the ERD below, display all fields in the JOB table sorted by the largest hourly charges for the job first.arrow_forward
- A Guide to SQLComputer ScienceISBN:9781111527273Author:Philip J. PrattPublisher:Course Technology PtrNp Ms Office 365/Excel 2016 I NtermedComputer ScienceISBN:9781337508841Author:CareyPublisher:Cengage