Computer Science – 8.3 Data Definition Language (DDL) and Data Manipulation Language (DML) | e-Consult
8.3 Data Definition Language (DDL) and Data Manipulation Language (DML) (1 questions)
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To accommodate a new data element, the database administrator would typically follow these steps:
- Analyze the Requirement: Determine where the new data element should be stored (which table) and what data type it should have.
- Create a DDL statement: Write a DDL statement (usually an ALTER TABLE statement) to add a new column to the appropriate table. This statement specifies the column name, data type, and any constraints.
- Execute the DDL statement: The database administrator executes the DDL statement using a database management tool (e.g., SQL client).
- Verify the change: After executing the DDL statement, the database administrator verifies that the new column has been added to the table and that the data type is correct.
Here's a simple example:
| Initial Table Structure: |
| Table Name: Customers |
| Columns: |
| CustomerID (INT, Primary Key) |
| Name (VARCHAR(255)) |
Modified Table Structure (with 'Email' column):
| Table Name: Customers |
| Columns: |
| CustomerID (INT, Primary Key) |
| Name (VARCHAR(255)) |
| Email (VARCHAR(255)) |
In this example, the ALTER TABLE statement would be: ALTER TABLE Customers ADD Email VARCHAR(255); The DBMS would then update the table structure to include the new 'Email' column. The DDL ensures that the database structure is modified correctly and consistently.