1.
A database language enables the user to perform complex queries designed to transform the raw data into useful information.
Correct Answer
A. True
Explanation
A database language allows users to execute complex queries that can manipulate and transform raw data into meaningful information. This enables users to retrieve specific data, perform calculations, combine data from multiple tables, and generate reports or analysis. By using a database language, users can efficiently extract the desired information from a database, making it a valuable tool for data analysis and decision-making.
2.
SQL is considered difficult to learn; its command set has a vocabulary of more than 300 words
Correct Answer
B. False
Explanation
The statement that SQL is considered difficult to learn because its command set has a vocabulary of more than 300 words is false. While SQL does have a wide range of commands and keywords, the difficulty of learning SQL is subjective and can vary from person to person. Some individuals may find SQL easy to learn, while others may struggle with it. The number of words in its command set does not necessarily determine its difficulty level.
3.
The COMMIT command does not permanently save all changes. In order to do that, you must use SAVE.
Correct Answer
B. False
Explanation
The statement is incorrect. The COMMIT command is used to permanently save all changes made in a transaction. It is not necessary to use the SAVE command for this purpose.
4.
All SQL commands must be issued on a single line.
Correct Answer
B. False
Explanation
This statement is false. In SQL, commands can be issued on multiple lines for better readability and organization. SQL statements can also be broken down into multiple lines using line breaks and indentation without affecting the execution of the command. Therefore, it is not necessary to issue all SQL commands on a single line.
5.
Although SQL commands can be grouped together on a single line, complex command sequences are best shown on separate lines, with space between the SQL command and the command’s components.
Correct Answer
A. True
Explanation
Complex command sequences are best shown on separate lines with space between the SQL command and its components because it improves readability and makes it easier to understand the structure of the command sequence. By separating the commands onto separate lines, it becomes clearer where one command ends and the next one begins. Additionally, adding space between the SQL command and its components helps to visually distinguish the different parts of the command, making it easier to identify and interpret each component. This practice is especially important for complex command sequences that involve multiple SQL commands and components.
6.
An alias cannot be used when a table is required to be joined to itself in a recursive query.
Correct Answer
B. False
Explanation
In a recursive query, a table can be joined to itself using an alias. This allows the query to refer to the same table multiple times within the same query. This is commonly used in situations where the query needs to reference different rows within the same table in order to perform calculations or retrieve specific data. Therefore, the statement "An alias cannot be used when a table is required to be joined to itself in a recursive query" is false.
7.
Comparison operators cannot be used to place restrictions on character-based attributes.
Correct Answer
B. False
Explanation
The statement is false because comparison operators can indeed be used to place restrictions on character-based attributes. Comparison operators such as "==" or "!=" can be used to compare character-based attributes and determine if they meet certain conditions or restrictions. Therefore, the correct answer is False.
8.
11. String comparisons are made from left to right.
Correct Answer
A. True
Explanation
String comparisons are made from left to right means that when comparing two strings, the comparison starts from the leftmost character and continues until a difference is found or the end of the strings is reached. This means that the characters in the strings are compared one by one in the order they appear. If a difference is found, the comparison stops and the result is determined based on the ASCII values of the differing characters. Therefore, the given statement "True" is correct.
9.
13. SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT.
Correct Answer
A. True
Explanation
SQL allows the use of logical restrictions such as OR, AND, and NOT in its inquiries. These logical operators allow users to combine conditions and create complex queries to retrieve specific data from a database. The OR operator allows the retrieval of data that satisfies at least one of the conditions, the AND operator retrieves data that satisfies all the conditions, and the NOT operator retrieves data that does not satisfy a particular condition. Therefore, the statement "SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT" is true.
10.
14. You cannot insert a row containing a null attribute value using SQL.
Correct Answer
B. False
Explanation
In SQL, it is possible to insert a row containing a null attribute value. The NULL value represents missing or unknown data, and it is allowed to be inserted into a table. Therefore, the statement "You cannot insert a row containing a null attribute value using SQL" is false.
11.
16. The conditional LIKE must be used in conjunction with wildcard characters.
Correct Answer
A. True
Explanation
The statement is true because the LIKE operator is used in SQL to perform pattern matching on a specified column. Wildcard characters, such as % and _, are used with the LIKE operator to represent unknown or multiple characters. Without the use of wildcard characters, the LIKE operator would not be able to match patterns effectively. Therefore, the conditional LIKE must be used in conjunction with wildcard characters to achieve the desired pattern matching functionality.
12.
19. The COUNT function is designed to tally the number of non-null "values" of an attribute, and is often used in conjunction with the DISTINCT clause.
Correct Answer
A. True
Explanation
The explanation for the given correct answer is that the COUNT function is indeed designed to count the number of non-null "values" of an attribute. It is commonly used in conjunction with the DISTINCT clause to count the unique non-null values in a column. Therefore, the statement is true.
13.
21. The SQL data manipulation command HAVING:
Correct Answer
B.
restricts the selection of grouped rows based on a condition.
Explanation
The SQL data manipulation command HAVING is used to restrict the selection of grouped rows based on a condition. It is used in conjunction with the GROUP BY clause to filter the results of a query based on aggregate functions or other conditions applied to grouped data. The HAVING clause is applied after the GROUP BY clause and allows you to specify conditions that must be met by the grouped rows in order to be included in the result set.
14.
22. The SQL command that allows a user to permanently save data changes is _____.
Correct Answer
C. COMMIT
Explanation
The SQL command "COMMIT" allows a user to permanently save data changes. When this command is executed, it confirms that all the changes made to the database should be saved permanently. It is used in conjunction with the "UPDATE" or "INSERT" commands to ensure that the changes made to the data are committed and not temporary. The "SELECT" command is used to retrieve data from the database and does not save any changes.
15.
23. The _____ command defines a default value for a column when no value is given.
Correct Answer
D. DEFAULT
Explanation
The DEFAULT command is used to define a default value for a column when no value is given. This means that if a value is not specified for the column during an insert operation, the default value will be used instead.
16.
24. The _____ command restricts the selection of grouped rows based on a condition.
Correct Answer
B. HAVING
Explanation
The HAVING command is used to restrict the selection of grouped rows based on a condition. It is typically used in conjunction with the GROUP BY clause to filter the results of a query based on aggregate functions such as COUNT, SUM, AVG, etc. The HAVING command allows you to specify conditions that must be met by the groups in order to be included in the result set.
17.
25. A(n) _____ query specifies which data should be retrieved and how it should be filtered, aggregated, and displayed.
Correct Answer
B. SELECT
Explanation
A SELECT query is used to specify which data should be retrieved from a database. It also allows for filtering, aggregating, and displaying the data based on specific criteria. This query is commonly used in SQL to retrieve information from tables and present it in a desired format.
18.
26. A(n) _____ is an alternate name given to a column or table in any SQL statement.
Correct Answer
A.
alias
Explanation
In SQL, an alias is an alternate name given to a column or table in any SQL statement. It is used to provide a temporary name to a column or table, which can be helpful in making the SQL statement more readable and concise. Aliases can also be used to rename the output of a query or to provide a shorter name for a table or column with a long name.
19.
30. A(n) _____ join will select only the rows with matching values in the common attribute(s).
Correct Answer
A. Natural
Explanation
A natural join will select only the rows with matching values in the common attribute(s). This means that it will combine the rows from two tables based on the values in the common attribute(s), and only include the rows where the values match.
20.
36. Which comparison operator indicates a value is not equal?
Correct Answer
D. <>
Explanation
The comparison operator "" is used to indicate that a value is not equal to another value. This operator is commonly used in programming languages and databases to compare two values and return true if they are not equal.
21.
38. The special operator used to check whether an attribute value is within a range of values is _____.
Correct Answer
A. BETWEEN
Explanation
The special operator used to check whether an attribute value is within a range of values is "BETWEEN". This operator is used in SQL queries to specify a range of values for a particular attribute. It allows for inclusive range comparisons, where the attribute value must be between two specified values.
22.
39. The special operator used to check whether an attribute value ro string pattern is _____.
Correct Answer
C. LIKE
Explanation
The special operator used to check whether an attribute value matches a string pattern is "LIKE". This operator is commonly used in SQL queries to perform pattern matching on string values. It allows for the use of wildcard characters such as "%" to represent any number of characters, and "_" to represent a single character. By using the "LIKE" operator, you can search for specific patterns within attribute values in a database.
23.
40. The SQL aggregate function that gives the number of rows containing non-null values for a given column is _____.
Correct Answer
A. COUNT
Explanation
The SQL aggregate function "COUNT" is used to count the number of rows that contain non-null values for a given column. It returns the total number of rows that meet the specified criteria. This function is commonly used to calculate the number of records in a table or the number of occurrences of a specific value in a column.
24.
41. A(n) _____ is a query that is embedded (or nested) inside another query.
Correct Answer
C. Subquery
Explanation
A subquery is a query that is embedded or nested inside another query. It is used to retrieve data from one or more tables and is typically placed within the WHERE or HAVING clause of the outer query. The result of the subquery is then used by the outer query to perform further operations or filtering. Subqueries are useful for performing complex queries and can help in simplifying the overall query structure.
25.
43. The special operator used to check whether a subquery returns any rows is _____.
Correct Answer
B. EXISTS
Explanation
The special operator EXISTS is used to check whether a subquery returns any rows. It returns a boolean value of true if the subquery returns at least one row, and false if it does not. This operator is often used in combination with the WHERE clause to filter results based on the existence of related records in another table.
26.
1. A view is a virtual table based on a SELECT query.
Correct Answer
A. True
Explanation
A view is a virtual table that is created based on the result of a SELECT query. It does not store any data itself but instead provides a way to access and manipulate data from one or more tables. By using views, users can simplify complex queries, restrict access to certain columns or rows, and present data in a more meaningful way. Therefore, the statement that "a view is a virtual table based on a SELECT query" is true.
27.
3. To remedy the lack of procedural functionality in SQL, and to provide some standardization within the many vendor offerings, the SQL-99 standard defined the use of persistent stored modules.
Correct Answer
A. True
Explanation
The SQL-99 standard introduced the concept of persistent stored modules to address the lack of procedural functionality in SQL and to bring some standardization across different vendor offerings. These modules allow developers to write and store procedural code directly in the database, making it easier to implement complex logic and improve performance. Therefore, the statement "True" is the correct answer.
28.
5. A persistent stored module is stored and executed on the database client machine.
Correct Answer
B. False
Explanation
A persistent stored module is not stored and executed on the database client machine. Instead, it is stored and executed on the database server machine. The purpose of a persistent stored module is to perform specific tasks or operations within the database server itself, rather than relying on the client machine to execute them. This allows for better performance and security, as the server can handle the processing and execution of the module.
29.
6. Every PL/SQL block must be given a name.
Correct Answer
B. False
Explanation
PL/SQL blocks are not required to have a name. PL/SQL blocks are anonymous blocks of code that can be executed without being explicitly named. These blocks can be used to group and organize code, but they do not necessarily need to be named. Therefore, the statement "Every PL/SQL block must be given a name" is false.
30.
7. In Oracle, you can use the SQL*Plus command SHOW ERRORS to help you diagnose errors found in PL/SQL blocks.
Correct Answer
A. True
Explanation
The SQL*Plus command SHOW ERRORS in Oracle is used to display the compilation errors that occur in PL/SQL blocks. This command is helpful in identifying and diagnosing errors in the code, allowing developers to quickly locate and fix any issues. Therefore, the given statement is true.
31.
8. The most useful feature of PL/SQL blocks is that they let a designer create code that can be named, stored, and executed by the DBMS.
Correct Answer
A. True
Explanation
PL/SQL blocks are a fundamental component of PL/SQL programming language. They allow designers to create reusable code that can be named, stored, and executed by the DBMS (Database Management System). This feature enhances code organization and reusability, making it easier to maintain and manage large codebases. Therefore, the statement is true.
32.
11. A trigger is procedural SQL code that is automatically invoked by the RDBMS upon the occurrence of a given data manipulation event.
Correct Answer
A. True
Explanation
A trigger is a type of procedural SQL code that is designed to automatically execute in response to a specific event occurring within a relational database management system (RDBMS). These events are typically data manipulation events, such as inserting, updating, or deleting data in a table. When the specified event occurs, the trigger is automatically invoked by the RDBMS, allowing it to perform a predefined set of actions or operations. Therefore, the statement "A trigger is procedural SQL code that is automatically invoked by the RDBMS upon the occurrence of a given data manipulation event" is true.
33.
12. Triggers can only be used to update table values.
Correct Answer
B. False
Explanation
Triggers can be used to perform various actions, including updating table values, but they are not limited to just updating table values. Triggers can also be used to insert, delete, or perform other actions based on certain conditions or events occurring in the database. Therefore, the statement "Triggers can only be used to update table values" is false.
34.
21. When you create a new database, the RDBMS automatically creates the data _____ tables in which to store the metadata and creates a default database administrator.
Correct Answer
C. Dictionary
Explanation
When you create a new database, the RDBMS automatically creates the data dictionary tables in which to store the metadata and creates a default database administrator. The data dictionary is a collection of database objects that contains information about the structure, definitions, and relationships of the database. It stores information such as table names, column names, data types, constraints, and indexes. The RDBMS automatically creates these tables to manage and maintain the metadata of the database. The default database administrator is also created to have the necessary privileges and permissions to manage the database.
35.
22. Which SQL format would be best used for a small, numeric data type?
Correct Answer
B. SMALLINT
Explanation
SMALLINT would be the best SQL format to use for a small, numeric data type. This data type is specifically designed to store small integer values, typically ranging from -32,768 to 32,767. It requires less storage space compared to INTEGER or NUMERIC data types, making it ideal for small numeric values. CHAR(L) is not suitable for numeric data types as it is used for storing character data, while NUMERIC(L,D) is used for storing decimal numbers and may not be necessary for small numeric values.
36.
30. Using the _____ command, SQL indexes can be created on the basis of any selected attribute.
Correct Answer
A. CREATE INDEX
Explanation
The CREATE INDEX command in SQL allows for the creation of indexes on selected attributes. Indexes are used to improve the performance of database queries by providing a quick access path to the data. By creating an index on a specific attribute, the database can efficiently locate and retrieve the desired information. This command is essential for optimizing query performance in SQL databases.
37.
31. All changes in a table structure are made using the _____ TABLE command, followed by a keyword that produces the specific changes a user wants to make.
Correct Answer
A. ALTER
Explanation
The correct answer is ALTER. In database management, the ALTER TABLE command is used to make changes to the structure of a table. It allows users to add, modify, or delete columns, as well as define constraints and indexes. The ALTER TABLE command is followed by a keyword that specifies the specific change the user wants to make, such as ADD, MODIFY, or DROP.
38.
32. A table can be deleted from the database by using the _____ TABLE command.
Correct Answer
A. DROP
Explanation
The correct answer is DROP. The DROP TABLE command is used to delete a table from the database. This command removes the entire table structure and all its data from the database. It is a commonly used command when a table is no longer needed or needs to be recreated with different structure or data.
39.
33. SQL requires the use of the _____ command to enter data into a table.
Correct Answer
A. INSERT
Explanation
SQL requires the use of the INSERT command to enter data into a table. The INSERT command allows users to add new rows of data into a specific table in the database. This command is essential for populating tables with the desired information and is a fundamental operation in SQL.
40.
34. The _____ command permanently saves all changes—such as rows added, attributes modified, and rows deleted—made to any table in the database.
Correct Answer
A. COMMIT
Explanation
The COMMIT command is used in databases to permanently save all changes made to a table. It is typically used after executing a series of SQL statements to ensure that the changes are permanently saved and not rolled back. This command is important for maintaining data integrity and consistency in a database.
41.
35. Which command would be used to delete the table row where the P_CODE is 'BRT-345'?
Correct Answer
A. DELETE FROM PRODUCT
WHERE P_CODE = 'BRT-345';
Explanation
The correct answer is "DELETE FROM PRODUCT WHERE P_CODE = 'BRT-345';" because the DELETE command is used to delete rows from a table, and the WHERE clause specifies the condition that must be met for the row to be deleted. In this case, the condition is that the P_CODE column must have a value of 'BRT-345'.
42.
37. The _____ command is used to restore the database to its previous condition.
Correct Answer
D. ROLLBACK
Explanation
The ROLLBACK command is used to restore the database to its previous condition. This command is typically used in situations where a transaction needs to be undone or rolled back due to an error or failure. It allows the database to revert back to the state it was in before the transaction started, ensuring data consistency and integrity.
43.
38. The tables on which a view, or a virtual table derived from a SELECT query, are based are called _____ tables.
Correct Answer
D. Base
Explanation
The tables on which a view or a virtual table derived from a SELECT query are based are called "base" tables. These base tables serve as the underlying source of data for the view or virtual table, providing the necessary information for the view to retrieve and display the desired data.
44.
45. The PL/SQL block starts with the _____ section.
Correct Answer
C. DECLARE
Explanation
The PL/SQL block starts with the DECLARE section. This section is used to declare variables, cursors, and other program objects that will be used within the block. It is where the programmer specifies the data types and initial values of the variables. Once the variables are declared, they can be used in the subsequent sections of the block, such as the BEGIN section where the actual logic of the program is written.
45.
50. No matter what language you use, if it contains embedded SQL statements, it is called the _____ language.
Correct Answer
C. Host
Explanation
The term "host" refers to the language that is used as the main programming language, which can be any language, as long as it contains embedded SQL statements. In other words, regardless of the specific programming language being used, if it includes embedded SQL statements, it is referred to as the host language.
46.
1. Most real-world database transactions are formed by only one database request.
Correct Answer
B. False
Explanation
Most real-world database transactions are not formed by only one database request. In a real-world scenario, a transaction typically involves multiple database requests to perform a series of operations. These operations may include retrieving data, updating records, inserting new data, or deleting existing data. By grouping these requests together as a single transaction, it ensures that all the operations either succeed or fail together, maintaining the integrity and consistency of the database. Therefore, the correct answer is False.
47.
2. Although the DBMS is designed to recover a database to a previous consistent state when an interruption prevents the completion of a required set of transactions, the transactions themselves are defined by the end user or programmer and must be semantically correct.
Correct Answer
A. True
Explanation
The statement is true because while a DBMS is designed to recover a database to a previous consistent state in the event of an interruption, the responsibility of defining the transactions and ensuring their semantic correctness lies with the end user or programmer. The DBMS can only ensure the consistency and integrity of the database based on the transactions it is provided with, but it does not have control over the correctness of the transactions themselves.
48.
4. Atomicity indicates the permanence of the database's consistent state.
Correct Answer
B. False
Explanation
Atomicity does not indicate the permanence of the database's consistent state. Atomicity refers to the property of a transaction in a database system where either all the operations within the transaction are successfully completed and committed, or none of them are. It ensures that if any part of the transaction fails, the entire transaction is rolled back and the database is left unchanged. Permanence of the database's consistent state is ensured by durability, which guarantees that once a transaction is committed, its changes are permanent and will survive any subsequent failures.
49.
5. Serializability means that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed.
Correct Answer
B. False
Explanation
Serializability means that the execution of concurrent transactions produces the same result as if the transactions were executed serially, one after the other. It ensures that the final state of the database is consistent and preserves the integrity of the data. However, it does not mean that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed. Multiple transactions can access and manipulate the same data concurrently, as long as the overall execution remains serializable.
50.
9. The scheduler establishes the order in which the operations within concurrent transactions are executed.
Correct Answer
A. True
Explanation
The scheduler is responsible for determining the order in which the operations within concurrent transactions are executed. This is important in ensuring that the transactions are executed in a consistent and correct manner, avoiding any conflicts or inconsistencies. By establishing a specific order for the operations, the scheduler can ensure that the transactions are executed in a way that maintains the integrity of the data and avoids any potential issues that may arise from concurrent execution.