Doing database refactoring and I want to change Primary key from one attribute to other in...
Doing database refactoring and I want to change Primary key from one attribute to other in the table. How to do it with Surrogate key?
Homework Answers
You need to first remove all the referential integrity constrains (FOREIGN KEY) from this table. Then drop the current PRIMARY KEY constraint from this table and create a new one. ALTER TABLE <table_name> DROP CONSTRAINT <pk_constraint>; ALTER TABLE <table_name> ADD CONSTRAINT <k_constraint> PRIMARY KEY (<new columns>);
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Doing database refactoring and I want to change Primary key from
one attribute to other in...
Some database designers think that, for consistency, if one table has a surrogate key, all tables in the database should. Others think that such a policy is too rigid. Which position do you support an...
Some database designers think that, for consistency, if one table has a surrogate key, all tables in the database should. Others think that such a policy is too rigid. Which position do you support and why? Try to illustrate with an example. Looking for opinions supporting either position! Just want to wrap my head around each concept's pros and cons. Thank you!
24) A key that contains more than one attribute is called a(n) A) composite key B)...
24) A key that contains more than one attribute is called a(n) A) composite key B) complex key C) multi-key D) n-key E) candidate key 25) Null values can cause problems because they are ambiguous. True False 26) In the normalization process, it is necessary to identify all the determinants in a relation. True False 27) To represent a relationship in the relational model, the primary key of one relation is placed into a second relation. True False 28) A...
Which of the following describes referential integrity? A. A Primary Key of a relational table must...
Which of the following describes referential integrity? A. A Primary Key of a relational table must not contain a null value B. One fact must not be in multiple places C. The value for a foreign key attribute must either be null or match the one of the data value of that attribute in the table in which the attribute is a primary key D. Referential Integrity is a principle that prevents the use of redundancy, avoids null values and...
16. The primary key is selected from the: Group of answer choices composite keys. foreign keys....
16. The primary key is selected from the: Group of answer choices composite keys. foreign keys. candidate keys. surrogate keys. 17. "Delete Table" statement is used to remove a table definition and all the data, indexes, triggers, constraints and permission specifications for that table. Group of answer choices True False 18. Which of the following commands always affect one row at a time when it runs? Group of answer choices Drop Insert Delete Update 19. Data stored as an image...
QUESTION 1 What is the most common relationship within a relational database? Select the best answer...
QUESTION 1 What is the most common relationship within a relational database? Select the best answer from the following. One-To-One relationship. o One-To-Many relationship. Many-To-Many relationship. Zero-To-Zero relationship. QUESTION 2 What is an "entity'? Select the best answer from the following. An entity, for our purposes, is the same as a table in the database. An entity represents one of the columns in an individual table. There are no entities in a relational database. Entities are only part of NoSQL...
The employee is table, the best candidate for primary key is Select one: a. Department ID...
The employee is table, the best candidate for primary key is Select one: a. Department ID b. Employee hiredate c. Employee ID d. Employee salary Question 2 A primary key can be composed of more than one attribute. Select one: True False Question 3 A foreign key allows you to join two tables. Select one: True False Question 4 Given two tables, department (dept_id, dept_location, dept_name) and EMPLOYEE(emp_id, emp_name, emp_dept_id, emp_name, emp_salary), which attribute (column) is the foreign key? Select...
I need unique answer, NO COPY OR HANDWRITING PLEASE! What is a Database key? Explain various...
I need unique answer, NO COPY OR HANDWRITING PLEASE! What is a Database key? Explain various types of database keys (Super key, Candidate key, Primary key and Foreign key) with your clear definitions/ideas and at least one appropriate example for each one of them.
A Pages entity in a relational database for tracking web browsing has the following attributes: PageID (the primary key, an integer number, required), PageURL (text, maximum 255 characters, required),...
A Pages entity in a relational database for tracking web browsing has the following attributes: PageID (the primary key, an integer number, required), PageURL (text, maximum 255 characters, required), IPAddress (text, maximum 15 characters, required), ViewDateTime (date and time the page was viewed, required). (a) Write an SQL Data Definition Language command to create the table for this entity. (b) Write an SQL Data Definition Language command to add a column for a new attribute to this table: ViewDuration (duration...
Database Concepts! please help Consider the following create table statements: create table R (a integer primary...
Database Concepts! please help
Consider the following create table statements: create table R (a integer primary key); create tables (b integer primary key, c integer references R(a) on update cascade); Assume that these tables have the following data inserted: R: (1) and (2) S: (1,1) and (2, 1) What happens when we want to delete the record (1) from R? The corresponding record from S and T will be deleted due to the cascade option Only the record in Rwill...
Given the data in the table the best surrogate primary key for this table would be:...
Given the data in the table the best surrogate primary key for
this table would be:
none of the listed attributes.
student, email, and instructor
student, email, and class
student, email, and day
instructor, phone
Student Roster Student Fred Flintstone [email protected] Wilma Flintstone [email protected] Wlima Flintstone [email protected] Barney Rubble BamBam Rubble [email protected] BamBam Rubble [email protected] Wilma Flintstone [email protected] Betty [email protected] Email Class Java Pramg M Java Pramg M Database Database Hacking Database Database Hacking Hacking...
24) A key that contains more than one attribute is called a(n) A) composite key B) complex key C) multi-key D) n-key E) candidate key 25) Null values can cause problems because they are ambiguous. True False 26) In the normalization process, it is necessary to identify all the determinants in a relation. True False 27) To represent a relationship in the relational model, the primary key of one relation is placed into a second relation. True False 28) A...
QUESTION 1 What is the most common relationship within a relational database? Select the best answer from the following. One-To-One relationship. o One-To-Many relationship. Many-To-Many relationship. Zero-To-Zero relationship. QUESTION 2 What is an "entity'? Select the best answer from the following. An entity, for our purposes, is the same as a table in the database. An entity represents one of the columns in an individual table. There are no entities in a relational database. Entities are only part of NoSQL...
Database Concepts! please help
Consider the following create table statements: create table R (a integer primary key); create tables (b integer primary key, c integer references R(a) on update cascade); Assume that these tables have the following data inserted: R: (1) and (2) S: (1,1) and (2, 1) What happens when we want to delete the record (1) from R? The corresponding record from S and T will be deleted due to the cascade option Only the record in Rwill...
Given the data in the table the best surrogate primary key for
this table would be:
none of the listed attributes.
student, email, and instructor
student, email, and class
student, email, and day
instructor, phone
Student Roster Student Fred Flintstone Most questions answered within 3 hours.
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