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Consider the following SQL table definition:
CREATE TABLE Orders (
OrderID INT PRIMARY KEY,
OrderDate DATE,
CustomerID INT,
CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE
);
What happens when a customer is deleted from the Customers table?
OrderID INT PRIMARY KEY,
OrderDate DATE,
CustomerID INT,
CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE
);
What happens when a customer is deleted from the Customers table?
- a)All corresponding rows in the Orders table will be deleted as well.
- b)The deletion of a customer will result in a foreign key violation in the Orders table.
- c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.
- d)No action will be taken in the Orders table.
Correct answer is option 'A'. Can you explain this answer?
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Most Upvoted Answer
Consider the following SQL table definition:CREATE TABLE Orders ( Ord...
The foreign key constraint in the Orders table is defined with ON DELETE CASCADE, which means that deleting a customer will delete all corresponding rows in the Orders table.
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Consider the following SQL table definition:CREATE TABLE Orders ( Ord...
Explanation:
When a customer is deleted from the Customers table, the behavior of the foreign key constraint defined on the Orders table comes into play. The foreign key constraint in this case is defined as ON DELETE CASCADE, which means that when a referenced row in the parent table (Customers) is deleted, all corresponding rows in the child table (Orders) will also be deleted.
This behavior is specified by the ON DELETE CASCADE clause in the foreign key constraint definition. It ensures that the integrity of the data is maintained by automatically deleting any dependent records in the child table when a referenced record in the parent table is deleted.
Example:
Let's consider an example to understand this behavior better. Suppose we have the following data in the Customers and Orders tables:
Customers table:
| ID | Name |
|----|--------|
| 1 | John |
| 2 | Alice |
| 3 | Robert |
Orders table:
| OrderID | OrderDate | CustomerID |
|---------|-----------|------------|
| 1 | 2021-01-01| 1 |
| 2 | 2021-02-01| 2 |
| 3 | 2021-03-01| 1 |
| 4 | 2021-04-01| 3 |
If we delete the customer with ID 1 from the Customers table, the following actions will occur:
1. The database system will check for any foreign key constraints defined on the Orders table.
2. It will find the foreign key constraint FK_Customer that references the Customers table.
3. The ON DELETE CASCADE clause specified in the constraint definition will be triggered.
4. As a result, all rows in the Orders table that have a CustomerID of 1 will be deleted.
5. After the deletion, the Orders table will only contain the following data:
Orders table:
| OrderID | OrderDate | CustomerID |
|---------|-----------|------------|
| 2 | 2021-02-01| 2 |
| 4 | 2021-04-01| 3 |
Thus, option A is the correct answer, as all corresponding rows in the Orders table will be deleted when a customer is deleted from the Customers table.
When a customer is deleted from the Customers table, the behavior of the foreign key constraint defined on the Orders table comes into play. The foreign key constraint in this case is defined as ON DELETE CASCADE, which means that when a referenced row in the parent table (Customers) is deleted, all corresponding rows in the child table (Orders) will also be deleted.
This behavior is specified by the ON DELETE CASCADE clause in the foreign key constraint definition. It ensures that the integrity of the data is maintained by automatically deleting any dependent records in the child table when a referenced record in the parent table is deleted.
Example:
Let's consider an example to understand this behavior better. Suppose we have the following data in the Customers and Orders tables:
Customers table:
| ID | Name |
|----|--------|
| 1 | John |
| 2 | Alice |
| 3 | Robert |
Orders table:
| OrderID | OrderDate | CustomerID |
|---------|-----------|------------|
| 1 | 2021-01-01| 1 |
| 2 | 2021-02-01| 2 |
| 3 | 2021-03-01| 1 |
| 4 | 2021-04-01| 3 |
If we delete the customer with ID 1 from the Customers table, the following actions will occur:
1. The database system will check for any foreign key constraints defined on the Orders table.
2. It will find the foreign key constraint FK_Customer that references the Customers table.
3. The ON DELETE CASCADE clause specified in the constraint definition will be triggered.
4. As a result, all rows in the Orders table that have a CustomerID of 1 will be deleted.
5. After the deletion, the Orders table will only contain the following data:
Orders table:
| OrderID | OrderDate | CustomerID |
|---------|-----------|------------|
| 2 | 2021-02-01| 2 |
| 4 | 2021-04-01| 3 |
Thus, option A is the correct answer, as all corresponding rows in the Orders table will be deleted when a customer is deleted from the Customers table.
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Consider the following SQL table definition:CREATE TABLE Orders ( OrderID INT PRIMARY KEY, OrderDate DATE, CustomerID INT, CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE);What happens when a customer is deleted from the Customers table?a)All corresponding rows in the Orders table will be deleted as well.b)The deletion of a customer will result in a foreign key violation in the Orders table.c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.d)No action will be taken in the Orders table.Correct answer is option 'A'. Can you explain this answer?
Question Description
Consider the following SQL table definition:CREATE TABLE Orders ( OrderID INT PRIMARY KEY, OrderDate DATE, CustomerID INT, CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE);What happens when a customer is deleted from the Customers table?a)All corresponding rows in the Orders table will be deleted as well.b)The deletion of a customer will result in a foreign key violation in the Orders table.c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.d)No action will be taken in the Orders table.Correct answer is option 'A'. 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 Orders ( OrderID INT PRIMARY KEY, OrderDate DATE, CustomerID INT, CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE);What happens when a customer is deleted from the Customers table?a)All corresponding rows in the Orders table will be deleted as well.b)The deletion of a customer will result in a foreign key violation in the Orders table.c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.d)No action will be taken in the Orders table.Correct answer is option 'A'. 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 Orders ( OrderID INT PRIMARY KEY, OrderDate DATE, CustomerID INT, CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE);What happens when a customer is deleted from the Customers table?a)All corresponding rows in the Orders table will be deleted as well.b)The deletion of a customer will result in a foreign key violation in the Orders table.c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.d)No action will be taken in the Orders table.Correct answer is option 'A'. Can you explain this answer?.
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Solutions for Consider the following SQL table definition:CREATE TABLE Orders ( OrderID INT PRIMARY KEY, OrderDate DATE, CustomerID INT, CONSTRAINT FK_Customer FOREIGN KEY (CustomerID) REFERENCES Customers(ID) ON DELETE CASCADE);What happens when a customer is deleted from the Customers table?a)All corresponding rows in the Orders table will be deleted as well.b)The deletion of a customer will result in a foreign key violation in the Orders table.c)The OrderDate column in the Orders table will be set to NULL for the corresponding rows.d)No action will be taken in the Orders table.Correct answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Software Development.
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