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Consider the following SQL table definition:
CREATE TABLE Employees (
ID INT PRIMARY KEY,
Name VARCHAR(50) NOT NULL,
DepartmentID INT,
CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID)
);
What would happen if the following DELETE statement is executed?
ID INT PRIMARY KEY,
Name VARCHAR(50) NOT NULL,
DepartmentID INT,
CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID)
);
What would happen if the following DELETE statement is executed?
DELETE FROM Departments WHERE ID = 1;
- a)The row will be successfully deleted.
- b)The row will not be deleted due to a primary key violation.
- c)The row will not be deleted due to a foreign key violation.
- d)The row will not be deleted due to a NULL value violation.
Correct answer is option 'C'. Can you explain this answer?
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Most Upvoted Answer
Consider the following SQL table definition:CREATE TABLE Employees ( ...
The Departments table has a foreign key constraint on the ID column, referenced by the Employees table. Therefore, deleting a row in the Departments table will result in a foreign key violation.
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Community Answer
Consider the following SQL table definition:CREATE TABLE Employees ( ...
Explanation:
When the DELETE statement is executed, it will attempt to delete a row from the "Departments" table where the ID is 1. However, since there is a foreign key constraint between the "Employees" and "Departments" tables, this deletion will not be allowed if there are any rows in the "Employees" table that reference the department with ID 1.
Foreign Key Constraints:
A foreign key constraint is a type of integrity constraint that ensures the data consistency between two related tables. It enforces that the values in the foreign key column (DepartmentID in this case) of the referencing table (Employees) must match the values in the primary key column (ID) of the referenced table (Departments).
Foreign Key Violation:
In this scenario, if there are any rows in the "Employees" table that have a DepartmentID of 1, the foreign key constraint will be violated when the DELETE statement is executed. This is because the foreign key constraint ensures that the DepartmentID values in the "Employees" table must exist in the "Departments" table.
Preventing Data Inconsistency:
By enforcing foreign key constraints, the database ensures that there are no orphaned records in the referencing table. If the row with ID 1 in the "Departments" table is deleted, it could leave some rows in the "Employees" table referencing a department that no longer exists. This would result in data inconsistency and potentially invalid references.
Consequences of Foreign Key Violation:
If the DELETE statement is executed and there are rows in the "Employees" table referencing the department with ID 1, the foreign key violation will prevent the deletion of the row from the "Departments" table. The database management system (DBMS) will raise an error indicating the violation, and the row will not be deleted.
Conclusion:
In summary, the DELETE statement will not be successful if there are any rows in the "Employees" table that reference the department with ID 1. The foreign key constraint ensures data consistency and prevents the deletion of a row that would result in orphaned records in the referencing table. Therefore, option (c) is the correct answer.
When the DELETE statement is executed, it will attempt to delete a row from the "Departments" table where the ID is 1. However, since there is a foreign key constraint between the "Employees" and "Departments" tables, this deletion will not be allowed if there are any rows in the "Employees" table that reference the department with ID 1.
Foreign Key Constraints:
A foreign key constraint is a type of integrity constraint that ensures the data consistency between two related tables. It enforces that the values in the foreign key column (DepartmentID in this case) of the referencing table (Employees) must match the values in the primary key column (ID) of the referenced table (Departments).
Foreign Key Violation:
In this scenario, if there are any rows in the "Employees" table that have a DepartmentID of 1, the foreign key constraint will be violated when the DELETE statement is executed. This is because the foreign key constraint ensures that the DepartmentID values in the "Employees" table must exist in the "Departments" table.
Preventing Data Inconsistency:
By enforcing foreign key constraints, the database ensures that there are no orphaned records in the referencing table. If the row with ID 1 in the "Departments" table is deleted, it could leave some rows in the "Employees" table referencing a department that no longer exists. This would result in data inconsistency and potentially invalid references.
Consequences of Foreign Key Violation:
If the DELETE statement is executed and there are rows in the "Employees" table referencing the department with ID 1, the foreign key violation will prevent the deletion of the row from the "Departments" table. The database management system (DBMS) will raise an error indicating the violation, and the row will not be deleted.
Conclusion:
In summary, the DELETE statement will not be successful if there are any rows in the "Employees" table that reference the department with ID 1. The foreign key constraint ensures data consistency and prevents the deletion of a row that would result in orphaned records in the referencing table. Therefore, option (c) is the correct answer.
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Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer?
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Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer? for Software Development 2024 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Software Development 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer?.
Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer? for Software Development 2024 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Software Development 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider the following SQL table definition:CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, DepartmentID INT, CONSTRAINT FK_Department FOREIGN KEY (DepartmentID) REFERENCES Departments(ID));What would happen if the following DELETE statement is executed?DELETE FROM Departments WHERE ID = 1;a)The row will be successfully deleted.b)The row will not be deleted due to a primary key violation.c)The row will not be deleted due to a foreign key violation.d)The row will not be deleted due to a NULL value violation.Correct answer is option 'C'. Can you explain this answer?.
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