1z0-071 Exam Dumps : Oracle Database 12c SQL

The query uses two functions: ROUND and TRUNC. The ROUND function will round the number 156.00 to the nearest hundred because of the -2 which specifies the number of decimal places to round to. This will result in 200. Then the TRUNC function truncates this number to the nearest 10, due to the -1 argument, which will give us 200 as the result since truncation does not change the rounded value in this case.

A. 16 (Incorrect)

B. 160 (Incorrect)

C. 150 (Incorrect)

D. 200 (Incorrect)

E. 100 (Incorrect)

Key components of an Entity-Relationship Model (ERM) include:

B. an attribute: Attributes are properties or characteristics of an entity, such as a person's name, date of birth, etc., and are essential in describing the data aspects of an entity in an ER model.

E. a relationship: Relationships describe how entities interact with each other within the database structure, such as a customer placing an order.

F. an entity: Entities are the key components of an ER model, representing objects or things within the domain that have a distinct existence, like 'Customer' or 'Order'.

Incorrect options:

A: A table is a database structure used to implement an entity in relational databases, not a component of the ER model itself.

C: While unique identifiers are crucial in database implementation (typically as primary keys), they are a specific attribute type, not a general component of ER models.

D: An activity is not a component of an ER model; activities relate more to process models or behavioral models in systems design.

In SQL, to return all rows from one table in a join regardless of whether they match rows in the other table, a LEFT JOIN is used when we want all rows from the left table, or a RIGHT JOIN when we want all rows from the right table. Here’s an explanation for each query provided in the context of the COLORS and BRICKS tables:

A. This query uses a LEFT JOIN and will return all the rows from the COLORS table (c) because it is on the left side of the join. Additionally, it joins the BRICKS table (b) on the condition that the color_rgb_hex_value matches. The condition in the WHERE clause (b.brick_id > 0) will not exclude any COLORS rows because it only filters the rows from the right table (BRICKS) after the join.

B. This query uses a RIGHT JOIN, and while it does return all rows from the COLORS table, it doesn't place it on the left side of the join, which is not what is typically expected from a RIGHT JOIN to return all rows from the right side table.

C. This query is a plain JOIN (also known as an inner join), which only returns rows that have matching values in both tables, so it will not return all the rows from the COLORS table if there is no match in the BRICKS table.

D. This query uses a FULL JOIN, which returns all rows when there is a match in one of the tables. Hence, it will return all the rows from both the COLORS and BRICKS tables. While this does return all rows from the COLORS table, it also includes all rows from the BRICKS table, which may not be desired if the requirement was only to return all rows from COLORS.

E. This query is similar to option A and uses the USING clause to specify the join condition. The USING clause is used when both tables have a column with the same name and is meant to simplify the syntax. However, in this case, the columns do not have the same name in both tables (RGB_HEX_VALUE in COLORS and COLOR_RGB_HEX_VALUE in BRICKS), so this query will not execute successfully.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Joins"

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "LEFT OUTER JOIN"

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "RIGHT OUTER JOIN"

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "FULL OUTER JOIN"

Based on the explanations above, the correct answers that return all rows from the COLORS table are A and D. However, D includes all rows from BRICKS as well, which may not be the intended requirement if the question specifies only rows from COLORS should be returned. Thus, A is the most accurate answer to the question as it adheres to the standard expectation of a LEFT JOIN.