使用python检查注册表是否已被删除

Question

How can I check if database data is missing?

 if cur.execute('DELETE FROM products WHERE shop = 5'):
       print('deleted sucess')

This code doesn't work and I didn't find how I can validate if the data has been deleted

Answer 1

You can delete then attempt to select what was deleted. This code should tell you if the delete was successful, though it's not very efficient... the database should delete the data and if it doesn't then you should pick a new database.

cur.execute('DELETE FROM products WHERE shop = 5')
cur.execute('SELECT * from products where shop = 5')
if not cur.fetchone():
    print('delete successful')

Answer 2

I am not 100% sure the motivation behind this extra check, but you can verify the cur.rowcount value, which returns the number of "affected rows" in your last query:

This read-only attribute specifies the number of rows that the last .execute*() produced (for DQL statements like SELECT ) or affected (for DML statements like UPDATE or INSERT ). [9]

cur.execute('DELETE FROM products WHERE shop = 5')

affected_rows = cur.rowcount
print("Rows affected: {affected_rows}".format(affected_rows=affected_rows))

if affected_rows > 0: 
    print('deleted success')