SQL_Puzzles.txt

*SQL Query Practice*

1. Extract all column names of a table that start with a vowel (uppercase/lowercase).

2. Find the number of NULLs in each column of a table (resultset should have 2 columns; first column lists table's column headers, second column lists no. of NULLs against each column header)

3. There's a table as STUDENT(*sid*, marks_maths, marks_physics, marks_chem, marks_CS), *sid* being PK non-NULL. Write a query to generate a resultset having columns as: _sid_, _max_marks_, _min_marks_, _avg_marks_.

4. A table COLORS stores the names of colors row-wise as depicted:

_Red,orange,green_
_blue,Yellow,magenta_
_Orange,Black,red_
_Green,Blue_
_magenta,Red_
_orange,yellow_

Write a query to group same colors in one row, first letter of each color capitalized (e.g. following resultset):

_Red,Red,Red_
_Orange,Orange,Orange_
_Green,Green_
_Magenta,Magenta_
_Yellow,Yellow_
_Black_

5. A table ROMAN_DATES has only 1 column containing 1 million dates in roman numeral format (e.g. XIIVMMXXIII is 12-05-2023). All dates in the column are valid & non-NULL. Write a query to transform every date into YYYY-MM-DD format (so XIIVMMXXIII would become 2023-05-12).