SQL
All Questions for: SQL
Question 51: What happens if you execute DELETE FROM table_name without a WHERE clause?
- A Nothing happens
- B All rows are deleted
- C Only first row is deleted
Explanation: The correct option is: Option B
Question 52: Which SQL keyword is used to give a column a temporary name?
- A RENAME
- B ALIAS
- C AS
Explanation: The correct option is: Option C
Question 53: Which SQL operator is used to test whether a value matches any value in a list?
- A IN
- B ANY
- C MATCHES
Explanation: The correct option is: Option A
Question 54: Which SQL comparison is used to check if a value is NULL?
- A value = NULL
- B value IS NULL
- C value == NULL
Explanation: The correct option is: Option B
Question 55: Is the SQL BETWEEN operator inclusive of boundary values?
- A Yes, it includes both values
- B No, it excludes both values
- C Yes, but only the lower value
Explanation: The correct option is: Option A
Question 56: Which statement is true regarding DROP and DELETE?
- A DROP removes rows, DELETE removes table
- B Both commands remove only rows
- C DELETE removes rows, DROP removes the table
Explanation: The correct option is: Option C
Question 57: Which SQL command is used to change an existing table structure?
- A ALTER TABLE
- B CHANGE STRUCTURE
- C MODIFY TABLE
Explanation: The correct option is: Option A
Question 58: What does COUNT(*) return in SQL?
- A The count of non-null values only
- B The total number of rows including NULLs
- C The count of unique values
Explanation: The correct option is: Option B
Question 59: Which SQL query updates salary to 50000 and commission to 10 for employee_id = 101?
- A UPDATE employees SET salary=50000, commission=10 WHERE employee_id=101;
- B UPDATE employees SET (salary, commission)=(50000,10) WHERE employee_id=101;
- C MODIFY employees SET salary=50000 AND commission=10 WHERE employee_id=101;
Explanation: The correct option is: Option A
Question 60: What happens if you execute DELETE FROM table_name without a WHERE clause?
- A Nothing happens
- B All rows are deleted
- C Only first row is deleted
Explanation: The correct option is: Option B