DA0-002 Data Concepts and Environments Practice Question
Exhibit
{
"employee": {
"emp_id": { "type": "integer", "nullable": false, "primary_key": true },
"name": { "type": "string", "nullable": false },
"email": { "type": "string", "nullable": true, "unique": true },
"department": { "type": "string", "nullable": true }
}
}Refer to the exhibit. A data architect is designing a data dictionary for a relational database. Based on the exhibit, which data concept is being illustrated?
⚠ Common exam trap
Candidates often confuse data constraints with data cardinality, because both involve 'rules' in a database, but cardinality specifically describes the nature of relationships between tables, not the column-level restrictions shown in the exhibit.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Data constraints
The exhibit shows a table definition with column attributes such as NOT NULL, UNIQUE, and PRIMARY KEY, which are data constraints that enforce rules on the data values. Data constraints ensure data integrity by restricting what data can be stored in a column, such as preventing null values or duplicate entries. This directly aligns with the concept of data constraints, making option A correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Data constraints
Why this is correct
The exhibit specifies field properties like nullable and unique, which are constraints on the data.
- ✗
Data aggregation
Why it's wrong here
Aggregation involves combining data, not defining field rules.
- ✗
Data normalization
Why it's wrong here
Normalization reduces data redundancy and improves integrity, but constraints are a separate concept.
- ✗
Data cardinality
Why it's wrong here
Cardinality defines the number of instances in a relationship, not field constraints.
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