Sql Functions

- The function `SELECT LOWER('COMPUTER')` converts the string to lowercase, so the correct answer for A is 'computer' (IV).
- The function `SELECT LEFT('COMPUTER', 3)` extracts the first three characters from the string 'COMPUTER', so the correct answer for B is 'com' (I).
- The function `SELECT RIGHT('COMPUTER', 4)` extracts the last four characters from the string 'COMPUTER', so the correct answer for C is 'ter' (II).
- The function `SELECT MID('COMPUTER', 2, 3)` extracts a substring starting from the second character and with a length of 3 characters, so the correct answer for D is 'omp' (III).
Therefore, the correct answer is "A-IV, B-I, C-II, D-III."

The SQL function \texttt{MOD()} returns the remainder of a division operation. In this case, \texttt{MOD(53, 10)} gives the remainder when 53 is divided by 10, which results in 3. Therefore, the correct function for this query is \texttt{MOD()}.

The `LIKE '\%5\%5\%'` SQL command searches for any string where two '5's appear in order, but not necessarily consecutively—they just need to appear somewhere in the value with any characters (including none) in between. Hence, it means the value contains two '5's in any position.

The SQL `ROUND()` function rounds a numeric field to the number of decimal places specified. `ROUND(765.3895, 2)` rounds the number to two decimal places. Since the third decimal digit is 9 (greater than 5), it rounds up from 765.38 to 765.39.

DATE(), NOW(), and DAY() are all valid Date Functions used in SQL. `DATE()` returns the current date, `NOW()` returns the current date and time, and `DAY()` extracts the day from a given date. However, `THEN()` is not a valid date function in SQL; it is typically used in `CASE` statements.
Therefore, the correct answer is "THEN()".

- ALTER is used to modify the structure of a table, such as renaming a column → I. - UPDATE is for changing values in existing records → III. - DELETE removes records (rows) from a table → IV. - CREATE initializes new objects like tables or databases → II.