databases Online Quiz - 156
|Description: databases Online Quiz - 156
|Number of Questions: 20
|Created by: Aliensbrain Bot
SYSDATE is a date function that returns the current database server date and time.
The value returned by the subquery is used by the main query.
When is a Cartesian product formed?
To answer this question, you need to understand the concept of a Cartesian product in the context of database joins.
A Cartesian product is formed when two tables are joined without any join condition specified. This means that all rows from the first table are combined with all rows from the second table, resulting in a combination of every row from the first table with every row from the second table.
Let's go through each option to understand why it is correct or incorrect:
Option A) When a join condition is omitted - This option is correct because a Cartesian product occurs when a join condition is not specified, resulting in the combination of all rows from both tables.
Option B) When a join condition is invalid - This option is incorrect because a Cartesian product occurs when no join condition is specified, regardless of whether the join condition is valid or not.
Option C) All rows in the first table are joined to all rows in the second table - This option is correct because a Cartesian product involves combining all rows from the first table with all rows from the second table.
Option D) All of the above - This option is correct because both option A and option C correctly describe when a Cartesian product is formed.
The correct answer is D) All of the above. This option is correct because a Cartesian product can occur when a join condition is omitted, when a join condition is invalid, or when all rows in the first table are joined to all rows in the second table.
Sorting SQL statement result data by column alias is not possible.
What are the two types of SQL Functions?
Single-Row Functions can return multiple results per row.
____________ is the outer join operator.
____________ is used to join a table to itself.
A null is the same as zero or a blank space.
To solve this question, the user needs to know the definition of a null value. A null value typically represents a missing or unknown value, and it is not the same as a zero or a blank space.
Option A - True: This option is incorrect. A null value is not equivalent to zero or a blank space. In programming, null is often used to indicate the absence of a value or a missing value.
Option B - False: This option is correct. A null value is not the same as zero or a blank space. It is a distinct value that represents an absence of data.
Therefore, the correct answer is:
The Answer is: B. False
What is the output of the following? SELECT ROUND(1111.93412,3) FROM DUAL;