Oracle Test 5

The statement is true because BULK COLLECT and FORALL statements in SQL allow for the processing of multiple rows of data at once, reducing the number of context switches between the SQL engine and the PL/SQL engine. This improves performance by minimizing the overhead associated with individual context switches for each row. By bulk collecting and processing data in batches, the number of context switches is reduced to a single switch, resulting in improved efficiency.

A sequence is a database object that generates a sequence of numbers. Once a sequence is created, it is associated with a specific schema, which is a logical container for database objects. This means that the sequence will be stored and accessed within that particular schema. Therefore, the statement "Once created, a sequence belongs to a specific schema" is true.

A MERGE statement can be used to insert new rows into a table. This statement combines the functionality of both INSERT and UPDATE statements. It allows you to insert new rows into a table if they do not already exist, or update existing rows if they do. Therefore, the statement "A MERGE statement can be used to insert new rows into a table" is true.

Explicit conversion is required for converting and displaying date/time data to character form and vice versa. This means that when we want to convert a date/time value to a character form, or vice versa, we need to explicitly specify the conversion method or function to perform the conversion. This is necessary because the data types of date/time and character are different, and therefore a specific conversion process is needed to ensure the correct representation and interpretation of the data.

The GROUP BY clause is placed after the WHERE clause in a SELECT statement. This is because the WHERE clause filters the data based on specified conditions before the grouping is done. Once the data is filtered, the GROUP BY clause is used to group the data based on one or more columns.

The correct answer is UPDATE. The question states that a new column of NUMBER data type has been added to the EMPLOYEES table to store phone numbers. To enter the phone numbers for each employee, an UPDATE operation is needed to update the existing records in the table with the corresponding phone numbers. INSERT would be used to add new records, not update existing ones. ADD and ENTER are not valid data manipulation operations. The statement "You cannot enter the phone numbers for the existing employee records" is incorrect, as the UPDATE operation allows for modifying existing records.

The correct answer is &&. The double ampersand (&&) is used as a substitution variable in SQL*Plus and Oracle SQL. It allows the user to reuse the variable without being prompted for its value each time. This is useful when running a script multiple times and wanting to use the same value for a variable without having to enter it repeatedly.

The correct answer is DESCRIBE. DESCRIBE is an SQL*Plus command that is used to retrieve information about a table, such as its structure, column names, and data types. It provides a description of the specified table, allowing users to understand the table's schema without having to query the database. This command is often used for debugging or when trying to understand the structure of a table before performing any operations on it.

Indexing is most useful when the indexed column contains a wide range of values. This is because indexing allows for faster retrieval of data based on specific values in the indexed column. When the column has a wide range of values, it means that there is a greater likelihood of needing to search for specific values within that range. By indexing the column, the database can quickly locate the desired values, improving the overall performance of queries and data retrieval.

The ROWID data type is a hexadecimal string that represents the unique address of a row in its table. It is used to identify a specific row in a table and is particularly useful for fast retrieval of data.

To execute a query on an existing view successfully, it is necessary to have SELECT privileges on the view. This means that the user executing the query must have the permission to retrieve data from the view. The underlying tables do not necessarily need to be in the same schema, and SELECT privileges on the underlying tables are not required, as the view acts as a virtual table that presents the data from the underlying tables.

The concatenation operator in programming languages like C and SQL is used to combine or join character strings and CLOB (Character Large Object) data. It allows you to merge two or more strings together to form a single string. This operator is commonly used for tasks like appending text to existing strings or combining multiple fields into a single field. Therefore, the statement "The concatenation operator manipulates character strings and CLOB data" is true.

The operator "NOT IN" can be used with a multiple-row subquery. This operator is used to exclude rows from the result set that are found in the subquery. It checks if the value on the left side of the operator is not present in the result set of the subquery. So, in this case, the "NOT IN" operator can be used to compare a value with multiple rows returned by a subquery and exclude any matching rows from the result.

The SCN_TO_TIMESTAMP function in Oracle can indeed be used to determine the latest timing of a change made to a specific table. SCN stands for System Change Number, which is a unique identifier for each change made in the database. By using the SCN_TO_TIMESTAMP function, the SCN value can be converted into a timestamp, allowing users to see the exact time when a change occurred. Therefore, the statement is true.

A subquery cannot be used in the GROUP BY clause of a SELECT statement. The GROUP BY clause is used to group rows based on a specific column or expression, and a subquery is a query nested within another query. The GROUP BY clause can only contain columns or expressions that are directly referenced in the SELECT statement. Therefore, it is not possible to use a subquery in the GROUP BY clause.

If all the parentheses are removed from the calculation, the order of operations in the calculation will still be maintained. The multiplication and addition operations will still be performed in the correct order, resulting in the same value being displayed in the CALC_VALUE column. Therefore, there will be no difference in the value displayed in the CALC_VALUE column.

A change to the DEFAULT value affects only subsequent insertions to the table. This means that the alteration to the SALARY column will not affect any existing rows in the table. Only new rows that are inserted after the alteration will have the default value of 5000 for the SALARY column.

The correct SQL statement to create an index called NAME_IDX on the first name and last name fields of the EMPLOYEES table is "CREATE INDEX NAME_IDX ON employees(first_name, last_name)". This statement specifies the index name, the table name, and the columns to be included in the index.

The given statement is false. TO_DATE is not a character manipulation function. It is a function used in SQL to convert a string into a date format. It takes a character string and a format mask as input and returns a date value.

The SQL statement SELECT ROUND(TRUNC(MOD(1600,10),-1),2)FROM dual; calculates the remainder of dividing 1600 by 10, which is 0. The TRUNC function then truncates this result to the nearest multiple of -1, which is also 0. Finally, the ROUND function rounds this result to 2 decimal places, which is still 0. Therefore, when this statement is evaluated, the value 0 will be displayed.

The statement says that if a sequence starting from 100 and incremented by 1 is used by more than one application, then all of these applications could have a value of 105 assigned to their column. However, this statement is false because if the sequence is incremented by 1, the next value after 100 would be 101, not 105. Therefore, it is not possible for all the applications to have a value of 105 assigned to their column.

When you execute the query, you obtain the results retrieved from the HR table that belongs to your schema. Since you have created a table with the same name in your schema, it takes precedence over the public synonym created by the database administrator. Therefore, the query will retrieve data from your own table rather than the public synonym.

Substitution variables in SQL*Plus can be used to replace values in the WHERE clause. These variables allow users to enter values at runtime, which can then be used in the query to dynamically filter the results. By using substitution variables, users can make their queries more flexible and adaptable to different scenarios without having to modify the query itself.

The given statement suggests that a role is created when the number of people using the database is very high. However, this is not true. A role is not created based on the number of people using the database. Instead, a role is created to assign specific privileges and permissions to a group of users, regardless of the number of users.

Group functions on columns do not include NULL values in calculations by default. If you want to include NULL values in calculations, you need to use the keyword INC_NULLS. Therefore, the statement "Group functions on columns include NULL values in calculations if you use the keyword INC_NULLS" is false.

The given SQL statement retrieves the employee name, salary, department ID, and maximum salary earned in the department of the employee. It does this by joining the "employees" table with a subquery that calculates the maximum salary for each department. The subquery is aliased as "b" and is grouped by department ID. The main query then filters the results by comparing the employee's salary with the maximum salary in their department. Only the employees who earn less than the maximum salary in their department are included in the result.

The statement "CREATE USER susan IDENTIFIED BY blue;" creates a new user named "susan" with the password "blue".

The correct answer is SELECT TO_CHAR(SYSDATE, 'FMDay, DD Month, YYYY') FROM dual; This SELECT statement uses the TO_CHAR function to convert the system date (SYSDATE) into a character string in the specified format 'FMDay, DD Month, YYYY'. The 'FM' format modifier is used to remove leading spaces and zeros.

The first true statement is that the sort is in ascending order by default when using the ORDER BY clause. This means that if the order is not specified as ascending or descending, the default behavior is to sort the results in ascending order.

The second true statement is that the ORDER BY clause comes last in the SELECT statement. This means that after specifying the columns to select and any other clauses like WHERE or GROUP BY, the ORDER BY clause is used to specify the sorting order of the results.

The SQL code provided calculates the average salary of the employees reporting to the same manager who were hired in the range just before through just after the employee. This is achieved by using the AVG function with the OVER clause and specifying the PARTITION BY manager_id to group the data by manager, and the ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING to define the range of rows to include in the calculation.

With 9i SQL Plus, you can enter PL/SQL blocks, SQL*Plus commands, and SQL commands at the command prompt. PL/SQL blocks are used for writing procedural code in Oracle databases. SQL*Plus commands are specific commands used within the SQL*Plus environment. SQL commands are used for querying and manipulating data in the database. Security commands are not mentioned as an option, so they cannot be entered at the command prompt.

The SELECT statement is trying to compare subj1 and subj2 with the AVG(subj1) and AVG(subj2) respectively. However, the AVG function cannot be used directly in the WHERE clause. To compare the marks with the average, a subquery or a derived table needs to be used. Since this is not done in the given SELECT statement, it results in an error at the WHERE clause.

The operator in the WHERE clause should be changed to display the desired results. In SQL, the correct way to check for null values is by using the "IS NULL" operator instead of the "=" operator. So, the correct statement should be "WHERE DEPARTMENT_ID IS NULL" instead of "WHERE DEPARTMENT_ID = NULL".

The guidelines for naming database tables include:
1) The table name must be 1-30 characters long.
2) It should not be an Oracle Server reserved word.
3) The table name must contain only A-Z, a-z, 0-9, _, $, and #.
4) The table name must begin with a letter.

The correct answer is that the DESCRIBE DEPT statement displays the structure of the DEPT table. This means that when the DESCRIBE DEPT statement is executed, it will show the column names, data types, and other information about the DEPT table. This is useful for understanding the structure of the table and its columns.

The given SQL statement selects the student_id, marks, and assigns a rank to each student based on their marks. The inner query selects the student_id and marks from the students table and orders them by marks in ascending order. The outer query then selects the student_id, marks, and assigns a row number as "Rank" to each student. The WHERE clause filters the result to only include the top 10 students. This statement will give a report of the 10 students who achieved the highest ranking in the course INT SQL and completed it in the year 1999.

The correct answer is "SELECT ename, salary*12 'Annual Salary' FROM employees;". This statement uses single quotes to define the alias "Annual Salary" for the calculated column SALARY*12.

The correct answer is the first option:

MERGE INTO new_employees c
USING employees e
ON (c.employee_id = e.employee_id)
WHEN MATCHED THEN
UPDATE SET
c.name = e.first_name ||’,’|| e.last_name
WHEN NOT MATCHED THEN
INSERT VALUES(e.employee_id, e.first_name ||’,
‘||e.last_name);

This statement uses the correct syntax for the MERGE statement. It specifies the target table (new_employees) and the source table (employees) using the USING clause. It then defines the join condition using the ON clause. The WHEN MATCHED clause is used to specify the action to be taken when a match is found, which in this case is to update the name column in the new_employees table. The WHEN NOT MATCHED clause is used to specify the action to be taken when no match is found, which in this case is to insert a new row into the new_employees table.

To obtain the definition of the view EMP_DEPT_VU, you can query the USER_VIEWS data dictionary view. This view contains information about all the views owned by the current user, including the text of the SELECT statement used to create the view. By querying this view, you can retrieve the definition of the EMP_DEPT_VU view and examine the SELECT statement used to create it.

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The MANAGE TABLESPACE system privilege allows you to perform various operations on a tablespace. These operations include taking the tablespace offline, beginning and ending a backup, taking the tablespace online, and making the tablespace read-only or read-write.

The given SQL statement "SELECT * From orders;" is used to retrieve data from a data table. It selects all columns (indicated by *) from the "orders" table. Therefore, the correct answers are "Viewing" and "Inserting" as this statement can be used to view the data in the "orders" table and insert new data into it.

Before making a tablespace read only, the tablespace must be online, meaning it is accessible and available for use. Additionally, there should not be any active rollback segments within the tablespace, as this can cause conflicts and inconsistencies. Lastly, the tablespace should not be involved in an open backup, as this can interfere with the read-only operation.

The correct answer is the last option: SELECT dept_id, MIN(salary), MAX(salary) FROM employees GROUP BY dept_id, salary HAVING MIN(salary) 15000. This statement uses the GROUP BY clause to group the data by department ID and salary. It then applies the HAVING clause to filter the results, only selecting departments where the minimum salary is less than 5000 and the maximum salary is more than 15000.

The correct answers are the third and fifth options. The third option retrieves orders with an inclusive total that ranges between 100.00 and 2000.00 dollars by using the BETWEEN operator. The fifth option also retrieves orders with an inclusive total that ranges between 100.00 and 2000.00 dollars by using the greater than or equal to (>=) operator.

Before using the RENAME DATAFILE command with the alter tablespace command, the database must be taken offline. Additionally, the database must be open in order to perform the rename operation. These conditions must be met in order to successfully rename a datafile.

A subquery can be used in the INTO clause of an INSERT statement to insert data from the result of the subquery into a table. It can also be used in the FROM clause of a SELECT statement to retrieve data from a subquery as a virtual table. Additionally, a subquery can be used in the WHERE clause of a SELECT statement to filter the result based on the result of the subquery. Lastly, a subquery can be used in the SET clause of an UPDATE statement to set the value of a column based on the result of the subquery.

The four valid Oracle constraint types are UNIQUE, NON UNIQUE, PRIMARY KEY, and CONSTANT. UNIQUE constraint ensures that each value in a column is unique and does not allow duplicate values. NON UNIQUE constraint allows duplicate values in a column. PRIMARY KEY constraint uniquely identifies each record in a table and does not allow duplicate or null values. CONSTANT constraint ensures that the value of a column remains constant and cannot be modified.

The four attributes of single row functions are:
1. Manipulate data items: Single row functions can perform operations on individual data items within a row.
2. Act on each row returned: Single row functions are applied to each row returned by a query or a table.
3. Return one result per row: Single row functions produce a single result for each row processed.
4. Accept arguments which can be a column or an expression: Single row functions can accept either a column or an expression as an argument.

Constraints enforce rules at the view level by specifying conditions that must be met for the view to be updated or modified. Constraints also enforce rules at the table level by defining conditions that must be met for data to be inserted, updated, or deleted in a table. Additionally, constraints prevent the deletion of a table if there are dependencies, meaning that if other tables or views rely on the data in the table, it cannot be deleted.