Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Transcribed Image Text:**Understanding Relations in Databases**
Here is a table representing a relation named R:
```
A B C
0 1 2
3 4 5
6 7 8
```
Based on this table, let's identify the following:
1. **The attributes of R**:
- The attributes of the relation R are A, B, and C, which correspond to the columns in the table.
2. **The schema of R**:
- The schema of R describes the structure of the relation, including its attributes. Hence, the schema of R is R(A, B, C).
3. **The tuples of R**:
- The tuples are the rows in the table. The tuples of R are (0, 1, 2), (3, 4, 5), and (6, 7, 8).
4. **The components of the tuples for each attribute of R**:
- For attribute A: 0, 3, 6.
- For attribute B: 1, 4, 7.
- For attribute C: 2, 5, 8.
**Question:**
Which of the following is NOT a true statement about relation R?
- **A.** The schema of R is R(A, B, C).
- **B.** (0, 3, 6) is a tuple of R.
- **C.** 4 is the value of the B-component of one of the tuples of R.
- **D.** (3, 4, 5) is a tuple of R.
**Analysis:**
- Statement A is correct, as the schema of R is indeed R(A, B, C).
- Statement B is incorrect. (0, 3, 6) is not a tuple of R; it seems to be the values from the first component of different tuples.
- Statement C is correct, as 4 is the value of the B-component of the second tuple (3, 4, 5).
- Statement D is correct, as (3, 4, 5) is indeed a tuple of R.
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