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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.
RELATIONAL DIAGRAM:
Relational Diagram is also known as Entity Relational 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. It describes how data is related to each other.
Given database tables:
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 |
Table Name: REGION
REGION_CODE | REGION_DESCRIPT |
1 | EAST |
2 | WEST |
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Chapter 3 Solutions
Database Systems: Design, Implementation, & Management
- Using tables named T1 and T2, write a query example for each of the three join types you described in Question 2. Assume that T1 and T2 share a common column named Cl.arrow_forwardProblems 27 and 28 are based on the following query: SELECT P_CODE, P_DESCRIPT, P_QOH, P_PRICE, V_CODE FROM PRODUCT WHERE P_QOH P_MIN AND P_MIN = P_REORDER AND P_REORDER = 50 ORDER BY P_QOH; What indexes would you recommend? Write the commands to create those indexes.arrow_forwardWhat is the difference between a PRIMARY KEY constraint and a UNIQUE constraint?arrow_forward
- What three join types are included in the outer join classification?arrow_forward1) List all the functional dependencies of the above table. (Note, this requires you to state all the functional dependencies, not just count the number). 2) What normal form(s) is the table currently in? Justify your answer.arrow_forwardCreate a new table named PRODUCT. The product table will have two attributes; product ID as integer, not null, and a primary key constraint set to unique. product description as varchar(30), not null specification. I am not sure how to do a primary key contraint set to unique. I believe I did the first two correct.arrow_forward
- Three tables are given Student: studentNO, firstName, lastName, studentProgram Professor: professorID, professorProgram, professorName Student_professor: studentNO, professorID, mentor Complete the following requirements: Using the UNION operator, do a full outer join to display the student last name student program, professor name and professor program. Referring to the model created in step 2, determine the PK/FK relationships to build the SQL joining the three Create a query/subquery to display student first name, last name and program. The student program must be same as that in the professor table and the professor program name starts with a ‘C’. This query will use a subquery and not a join.arrow_forwardImplement a new independent entity phone in the Sakila database. Attributes and relationships are shown in the following diagram: The diagram uses Sakila naming conventions. Follow the Sakila conventions for your table and column names: All lower case Underscore separator between root and suffix Foreign keys have the same name as referenced primary key Write CREATE TABLE and ALTER TABLE statements that: Implement the entity as a new phone table. Implement the has relationships as foreign keys in the Sakila customer, staff, and store tables. Remove the existing phone column from the Sakila address table. Step 2 requires adding a foreign key constraint to an existing table. Ex: ALTER TABLE customer ADD FOREIGN KEY (phone_id) REFERENCES phone(phone_id) ON DELETE SET NULL ON UPDATE CASCADE; Specify data types as follows: phone_id, phone_number, and country_code have data type INT. phone_type has date type VARCHAR(12) and contains strings like 'Home', 'Mobile', and 'Other'. Apply…arrow_forwardImplement a new independent entity phone in the Sakila database. Attributes and relationships are shown in the following diagram: The diagram uses Sakila naming conventions. Follow the Sakila conventions for your table and column names: All lower case Underscore separator between root and suffix Foreign keys have the same name as referenced primary key Write CREATE TABLE and ALTER TABLE statements that: Implement the entity as a new phone table. Implement the has relationships as foreign keys in the Sakila customer, staff, and store tables. Remove the existing phone column from the Sakila address table. Step 2 requires adding a foreign key constraint to an existing table. Ex: ALTER TABLE customer ADD FOREIGN KEY (phone_id) REFERENCES phone(phone_id) ON DELETE SET NULL ON UPDATE CASCADE; Specify data types as follows: phone_id, phone_number, and country_code have data type INT. phone_type has date type VARCHAR(12) and contains strings like 'Home', 'Mobile', and 'Other'. Apply…arrow_forward
- Implement a new independent entity phone in the Sakila database. Attributes and relationships are shown in the following diagram: The diagram uses Sakila naming conventions. Follow the Sakila conventions for your table and column names: All lower case Underscore separator between root and suffix Foreign keys have the same name as referenced primary key Write CREATE TABLE and ALTER TABLE statements that: Implement the entity as a new phone table. Implement the has relationships as foreign keys in the Sakila customer, staff, and store tables. Remove the existing phone column from the Sakila address table. Step 2 requires adding a foreign key constraint to an existing table. Ex: ALTER TABLE customer ADD FOREIGN KEY (phone_id) REFERENCES phone(phone_id) ON DELETE SET NULL ON UPDATE CASCADE; Specify data types as follows: phone_id, phone_number, and country_code have data type INT. phone_type has date type VARCHAR(12) and contains strings like 'Home', 'Mobile', and 'Other'. Apply…arrow_forwardWhat data types would you use for the attributes in this entity? How would you code a CREATE TABLE statement to implement this entity as a table in the database?arrow_forwardConsidering the attached E-R diagram; provide SQL statements for the following cases: Create above relations for the E-R diagram above After creating each relation, insert at least 6 rows (tuples) for each relation (table) with data that you invented SALE_ITEM relation should include at least two same SaleID Update a “Price” value of a row in the ITEM relation Updated ITEM (ItemID) should be in SALE_ITEM The solution should include screenshots of your relations with data. Discuss issues while solving the above problems and any assumptions that you made.arrow_forward
- COMPREHENSIVE MICROSOFT OFFICE 365 EXCEComputer ScienceISBN:9780357392676Author:FREUND, StevenPublisher:CENGAGE LDatabase Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781305627482Author:Carlos Coronel, Steven MorrisPublisher:Cengage LearningDatabase Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781285196145Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos CoronelPublisher:Cengage Learning
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