How to compare data from a table with null?

Question

Python

Tell me how you can compare the data from the table with zero
. There is such a code:

@bot.command(aliases = ['warn'])
async def __warn(ctx, member: discord.Member = None, arg: int = None):
  print('1')
  if member is None:
    await ctx.send('Пользователь')
    print('2')
  elif arg is None:
    await ctx.send('Причина')
    print('3')
  else: 
    for i in cursor.execute("SELECT Wreason FROM users WHERE id = {}".format(member.id)).fetchone():
      if i == 0:
        print('4')
        cursor.execute("UPDATE users SET warns = warns + {1} WHERE id = {}".format(member.id))
        cursor.execute("UPDATE users SET Wreason = Wreason + {} WHERE id = {}".format(arg, member.id))

Condition: if the number from the table is 0, then we change the value in the warns and Wreason tables

Answer 1

Instead of

for i in cursor.execute("SELECT Wreason FROM users WHERE id = {}".format(member.id)).fetchone():
      if i == 0:
        print('4')
        cursor.execute("UPDATE users SET warns = warns + {1} WHERE id = {}".format(member.id))
        cursor.execute("UPDATE users SET Wreason = Wreason + {} WHERE id = {}".format(arg, member.id))

Use SQL Syntax Directly

cursor.execute("UPDATE users SET warns = warns + 1, Wreason = {} WHERE id = {} AND Wreason = 0".format(arg, member.id))

Updates the users table for the given user (increases the warning counter by 1, puts in a new reason for the warning), if Wreason = 0 before.