To determine which columns would have an index automatically created when executing the given SQL statement, we need to consider the following:

1. The "UNIQUE" constraint on the "SER_NO" column would automatically create an index for that column (Option A).

2. The "PRIMARY KEY" constraint on the combination of "ORDER_ID" and "ORDER_DATE" columns would automatically create a composite index on those columns (Option F).

Therefore, the correct answer is options A and F.

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To evaluate the given SQL statement TRUNCATE TABLE DEPT;, let's go through each option to determine which are true:

Option A) It releases the storage space used by the table - This option is true. The TRUNCATE statement removes all rows from the table and releases the storage space used by the table.

Option B) It does not release the storage space used by the table - This option is false. As mentioned above, the TRUNCATE statement does release the storage space used by the table.

Option C) You can roll back the deletion of rows after the statement executes - This option is false. The TRUNCATE statement cannot be rolled back. Once the statement executes, the rows are permanently deleted.

Option D) You can NOT roll back the deletion of rows after the statement executes - This option is true. As mentioned above, the TRUNCATE statement cannot be rolled back.

Option E) An attempt to use DESCRIBE on the DEPT table after the TRUNCATE statement executes will display an error - This option is false. After the TRUNCATE statement executes, the table structure remains intact. You can still use DESCRIBE or any other metadata query on the table.

Option F) You must be the owner of the table or have DELETE ANY TABLE system privileges to truncate the DEPT table - This option is true. To truncate a table, you need to have the necessary privileges. Typically, you must either be the owner of the table or have the DELETE ANY TABLE system privilege.

Therefore, the correct options are A, D, and F.

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To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value. - This option is incorrect. The NEXTVAL pseudo column is used to retrieve the next value from a sequence, not just to look at it without retrieving it.

Option B) You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. - This option is correct. The CURRVAL pseudo column is used to retrieve the current value generated from a sequence without affecting the sequence itself.

Option C) You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence. - This option is correct. The NEXTVAL pseudo column is used to retrieve the next value from a sequence by actually retrieving it from the sequence.

Option D) You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column. - This option is incorrect. The CURRVAL pseudo column is used to retrieve the current value generated from a sequence, not to generate a new value.

Option E) If a sequence starting from a value 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 whose value is being generated by the sequence. - This option is incorrect. Each application will retrieve the next value from the sequence independently, so they will receive different values. In this case, each application will receive a different value after 100.

Option F) You use a REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence. - This option is incorrect. The REUSE clause is not used to restart the sequence once it reaches the maximum value. It is used when dropping and recreating a sequence to reuse the existing values.

The correct answers are B) You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. and C) You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.

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To answer this question, we need to understand how to generate an alias for a calculated column in SQL.

Option A) SELECT ename, salary*12 'Annual Salary' FROM employees; - This option is incorrect because it uses single quotes (' ') to define the alias. In SQL, single quotes are used to define string literals, not column aliases.

Option B) SELECT ename, salary*12 "Annual Salary" FROM employees; - This option is correct because it uses double quotes (" ") to define the alias. In SQL, double quotes are used to define column aliases. Therefore, the alias "Annual Salary" is correctly generated for the calculated column salary*12.

Option C) SELECT ename, salary*12 AS Annual Salary FROM employees; - This option is incorrect because it uses the keyword AS without double quotes to define the alias. In SQL, the AS keyword is used to define aliases, but the alias itself should be enclosed in double quotes.

Option D) SELECT ename, salary*12 AS INITCAP("ANNUAL SALARY") FROM employees - This option is incorrect because it uses the INITCAP function within the alias definition. The INITCAP function is used to capitalize the first letter of each word in a string. It is not necessary in this case, as the alias "Annual Salary" does not require any special formatting.

The correct answer is B) B. SELECT ename, salary*12 "Annual Salary" FROM employees. This option correctly generates the alias "Annual Salary" for the calculated column salary*12.

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To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) SELECT &1, "&2" FROM &3 WHERE last_name = '&4'; This option is incorrect because it does not properly handle the user input. The column names, table name, and WHERE condition should be replaced using placeholders (&1, &2, &3, &4), but the WHERE condition is using a string literal ('&4') instead of a placeholder.

Option B) SELECT &1, '&2' FROM &3 WHERE '&last_name = '&4''; This option is incorrect because it also does not properly handle the user input. The WHERE condition is using a string literal ('&last_name = '&4'') instead of a placeholder. Additionally, there is a syntax error with an extra single quote before 'last_name'.

Option C) SELECT &1, &2 FROM &3 WHERE last_name = '&4'; This option is correct because it properly handles the user input. The column names, table name, and WHERE condition are replaced using placeholders (&1, &2, &3, &4). The WHERE condition also uses a placeholder for the user input.

Option D) SELECT &1, '&2' FROM EMP WHERE last_name = '&4'; This option is incorrect because it does not allow the user to input the table name. The table name is hardcoded as 'EMP'.

The correct answer is C. This option is correct because it accepts user input for the columns to be displayed, the table name, and the WHERE condition using placeholders.

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To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) The indexed column is declared as NOT NULL - This option is incorrect because declaring a column as NOT NULL does not necessarily make an index more useful. A NOT NULL constraint ensures that the column cannot have null values, but it does not directly affect the usefulness of an index.

Option B) The indexed columns are used in the FROM clause - This option is incorrect because using indexed columns in the FROM clause does not necessarily make an index more useful. The FROM clause is used to specify the tables from which to retrieve data, and while indexes can be used to optimize the retrieval of data, using indexed columns in the FROM clause alone does not guarantee the usefulness of an index.

Option C) The indexed columns are part of an expression - This option is incorrect because having indexed columns as part of an expression does not necessarily make an index more useful. While indexes can be used to optimize the evaluation of expressions, having indexed columns as part of an expression alone does not guarantee the usefulness of an index.

Option D) The indexed column contains a wide range of values - This option is correct because when the indexed column contains a wide range of values, an index can be more useful. Indexes are particularly effective when the indexed column has a large number of distinct values. A wide range of values in the indexed column allows for better selectivity, meaning that the index can filter out a larger portion of the data, resulting in improved query performance.

The correct answer is D. The indexed column contains a wide range of values. This option is correct because having a wide range of values in the indexed column makes an index more useful.

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