Microsoft Azure Data FundamentalsDescribe how to work with relational data on AzureEasy
A data engineer is working with an Azure SQL Database. The database stores sensor readings where each reading has a unique identifier that needs to be automatically generated and incremented for every new record. Which property should be assigned to the SensorID column to achieve this?
- AUNIQUE
- BPRIMARY KEY
- CIDENTITY
- DDEFAULT
Show answer & explanationAnswer & explanation
Correct answer: C. IDENTITY
The IDENTITY property automatically generates sequential numeric values for a column, which is precisely what's needed for an auto-incrementing unique identifier.
Why the other options are wrong
- A. UNIQUE ensures that all values in a column are distinct, but it does not automatically generate values.
- B. PRIMARY KEY ensures uniqueness and defines a clustered index, but it does not automatically generate values.
- D. DEFAULT specifies a default value for a column when no value is explicitly provided during an INSERT, but it's not for auto-incrementing sequential IDs.
IDENTITY Property (SQL)
The IDENTITY property in SQL Server automatically generates sequential numeric values for a column when new rows are inserted into a table.
- Auto-increments numeric values.
- Guarantees uniqueness within the column.
- Often used for primary key columns.
Memory trick: IDENTITY for Incremental ID.