IT Fundamentals: C Programming, UNIX, and SQL/Oracle

This conversion character is used to display strings in the output statement.

Quick sort algorithm works by partitioning the array to be sorted and each partition is in turn sorted recursively.

This type of sorting performs sorting on the secondary memory.

This command in UNIX is used to write first 'N' numbers of lines to the screen.

 This option is correct as we know that an identifier is an arbitrarily long sequence of letters and digits, the first character must be a letter, the underscore (_) counts as a letter, Upper case and lower case letters are different and all characters are significant. Since the given option contains all these properties, hence it is a valid identifier.

In UNIX, directory files contain the list of file names and the associated information.

This option is correct as the standard library function tellg() is defined in the header file iostream.h.

This option is used in UNIX to list entries by columns.

This option is correct as we know that a real constant in exponent form has two parts: a mantissa and an exponent. The mantissa must be either an integer or a proper real constant. The mantissa is followed by a letter E or e and the exponent, the exponent must be an integer. As the given option statisfies all these conditions, hence it is a valid real constant in exponent form.

This option is correct as double is not a derived data type rather it is a fundamental data type used for double precision floating point numbers, it is used for handling floating point numbers but it is treated a distinct data type because it occupies twice as much memory as type float and stores floating point numbers with much larger range and precision, hence it is NOT a derived data type.

 This option is correct because we use double hash sign (##) for operators to perform token replacement and merging during the preprocessor scanning phase.

This answer is correct. TRUNCATE statement is a DDL (Data Definition Language) statement but not a DML (Data Manipulation Language) statement. TRUNCATE statement when executed will remove all rows from the given table and will automatically commit the transaction.

This answer is correct. TRUNCATE command is a DDL (Data Definition Language) command, which is used to remove all the rows from a given table without rollback. Since it is a DDL (Data Definition Language) command, it automatically commits the transaction. DELETE command is a DML (Data Manipulation Language) command, which is used to remove all the rows from a given table with rollback option.

This answer is correct. 'Dbtimezone' is the keyword to get the timezone of the current DB. It gives the current timezone in which the database is existing.

This answer is correct. Two rows for a given column having UNIQUE key can have nulls. In Oracle, there is an exception that two rows can have nulls though the UNIQUE key is defined for the given column.

This answer is correct. Oracle generates a unique number, which is rowid from dual, i.e. AAAAB0AABAAAAOhAA.  RowID is an unique value for each record in a table.

This answer is correct. A primary key by default checks for both not null and the uniqueness conditions. Primary key will verify whether the value inside the column is null or not, and also unique from the other values or not. A primary key can also be a composite key. It can have one or more columns as a primary key.

This answer is correct. In Oracle, TO_CHAR is the function used to convert from number to a string. If any string is given to TO_CHAR, the result will still remain in string.

This option is correct as this declaration of array is valid.

This answer is correct. ALTER TABLE command is used to disable the primary key. To enable the primary key, along with ALTER TABLE command, USING INDEX and TABLESPACE also must be specified along with the command.

This answer is correct because for enabling primary key constraint, ALTER TABLE is used followed by ENABLE key word. Similarly, for disabling primary key constraint, index will be dropped because the index comes along with primary key by default and since primary key constraint is not applied on the records, the index is also dropped.

This answer is correct. SYSDATE+1 will give the next date and time component. But SYSDATE+1/86400 will give the next second of the current date and current hour and current minute because in a given day, there are 86400 seconds, i.e. 24 * 60 * 60 seconds. Hence 1/86400 will give you the current second. When the sysdate is added to 1/86400, it gives the next second of the current date, hour and minute.

 This option is correct as && (AND) operator is not a unary operator as it needs two values (two operands) for performing any operation.

This option is correct because the execution time of one loop is 10 seconds and since the loop runs 4 times, hence the total time of program execution will be 40 seconds.

This option is correct because when the compiler prints 'I am the best' for the very first time, it subsequently reads exit() and the program execution comes to an end. Hence, the statement will be printed only once.