Which of the following functions returns the substring from a given string ?

1. MID
2. INSTR
3. SUBSTR
4. CHAR

Which of the following functions returns the position of a substring in a given string ?

1. MID
2. INSTR
3. SUBSTR
4. CHAR

Which of the following SQL functions does not belong to the Math functions category ?

1. POWER()
2. ROUND()
3. LENGTH()
4. MOD()

Which of the following is not a valid aggregate function in MYSQL ?

1. COUNT()
2. SUM()
3. MAX()
4. LEN()