Draw an ER diagram that best represents the following situation. There are three types of accounts in a bank, with these attributes:
1. Checking: Acct-no, Date-opened, Balance, Service-charge
2. Savings: Acct-no, Date-opened, Balance, Interest-rate
3. Loan: Acct-no, Date-opened, Balance, Acct-limit
To draw an ER diagram that represents the situation described, we need to identify the entities and the relationships between them.
Entities:
1. Account: This is the main entity that represents all types of accounts in the bank. It has the following attributes:
- Acct-no: Account number
- Date-opened: The date when the account was opened
- Balance: The current balance of the account
2. Checking: This entity represents the checking accounts. It has an attribute Service-charge.
3. Savings: This entity represents the savings accounts. It has an attribute Interest-rate.
4. Loan: This entity represents the loan accounts. It has an attribute Acct-limit.
Relationships:
1. Account can be of three types: Checking, Savings, or Loan. This is a specialization/generalization relationship.
2. Each type of account (Checking, Savings, Loan) is a subtype of the Account entity. This is a subtype/supertype relationship.
Based on the above information, the ER diagram can be represented as follows:
+------------+
| Account |
+------------+
| Acct-no |
| Date-opened|
| Balance |
+------------+
△ △
| |
+------+ +------+
|Checking| |Savings|
+------+ +------+
|Service-| |Int- |
|charge | | Rate|
+--------+ +------+
+------+
| Loan |
+------+
|Limit |
+------+
In the above diagram, the Account entity is the main entity that has all the common attributes of all types of accounts. Checking, Savings, and Loan entities are subtypes of Account and have specific attributes for each type.
Please note that this is a simplified ER diagram, and in a real-world scenario, there might be more entities and relationships to consider.