How to execute the except block if try prints an empty string

Question

I want to search a record in a SQL table and if that record is not found, I want to print an error message. I am using a try/except block to do that. But, the error message is not shown. What I think is happening is that when SQL fails to find that record, it won't raise an error. It will just print an empty line. So, the except block is not being executed as python thinks the try block was executed successfully.

Code:

import mysql.connector as sql

mydb = sql.connect(host = "localhost", user = "root", passwd = "password", database = "menagerie")

mycursor = mydb.cursor()

try:
    mycursor.execute("SELECT * FROM pet  where name='Fluff'")
    data = mycursor.fetchall()
    for i in data:
        print(i)

except:
    print("Not found")

Here, in the table pet, there is no record having the name Fluff. So, I want to print the "Not Found" message. But, python prints an empty string.

If there is any way to solve the problem, whether using try/except or any other method, please do let me know. Thanks.

Check if data is an empty list.

John Gordon
– John Gordon

2020-11-28 05:36:30 +00:00
Commented Nov 28, 2020 at 5:36 — John Gordon
– John Gordon, Commented Nov 28, 2020 at 5:36

a121 · Accepted Answer · 2020-11-28 05:47:05Z

1

when there are no records satisfying the given condition (name='Fluff' in your case), mysql returns an empty set and no error is produced.

mysql> select * from job;
+-----+-------------+--------+
| Eno | designation | salary |
+-----+-------------+--------+
|   1 | PGT         |  21000 |
|   3 | TGT         |  19000 |
|   4 | PGT         |  23000 |
|   5 | Primary     |  12000 |
+-----+-------------+--------+
4 rows in set (0.02 sec)

mysql> select * from job where Eno=7;
Empty set (0.00 sec)

Instead of using a try and except block, you could check whether data is an empty list

mycursor.execute("SELECT * FROM pet  where name='Fluff'")
data = mycursor.fetchall()
if bool(data)==False:
      print("Not found")
else:     
      for i in data:
           print(i)

answered Nov 28, 2020 at 5:47

a121

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Comments

Ahmed · Accepted Answer · 2020-11-28 06:12:55Z

1

You've to include the exception you want so, the exception pop-up:

try:
    mycursor.execute("SELECT * FROM pet  where name='Fluff'")
    data = mycursor.fetchall()
    for i in data:
        print(i)

except sql.Error as err:
    print("Error Code: ", err)

answered Nov 28, 2020 at 6:12

Ahmed

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3 Comments

Shounak Das Over a year ago

Thanks for trying to help. But, here, the except block isn't executing. So, the error code won't be printed.

Ahmed Over a year ago

Can you provide demo from from your data, please? Because i want to check how many items in your tuple output.

Shounak Das Over a year ago

There are 9 records. Click this link to download the sample database. downloads.mysql.com/docs/menagerie-db.zip

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