Data cleaning

is null

Finds whether a variable is NULL

• PHP is_null
• Google spreadsheet:
  • ISERR(value) " value - The value to be verified as an error type other than #N/A." ex: #NULL!
  • If the value is exactly NULL not #NULL!, You may use EXACT(value, "NULL")
• MySQL SELECT * FROM table WHERE column IS NULL;

Finds whether a variable is NOT NULL

• MySQL SELECT * FROM table WHERE column IS NOT NULL;