Capturing error from MySQL database.

import mysql.connector
try:
    my_connect = mysql.connector.connect(
      host="localhost",
      user="",
      passwd="",
      database="my_tutorial"
    )
except mysql.connector.Error as my_error:
    print(my_error.msg)  #  Error message
    print(my_error)      #  With error number 
####### end of connection ####

my_cursor = my_connect.cursor()
try:
    my_cursor.execute("SELECT * FROM  student1 Where class='Five'")

    print("Rows returned = ",my_cursor.rowcount)
    my_result = my_cursor.fetchone()
    print(my_result)
except mysql.connector.Error as my_error:
    print(my_error) # Output error details. 
my_connect.close()

1146 (42S02): Table 'my_tutorial.student1' doesn't exist

Example 1: Handling Specific Error Codes

import mysql.connector
try:
    my_connect = mysql.connector.connect(host="localhost", user="root", passwd="", database="my_tutorial")
    my_cursor = my_connect.cursor()
    my_cursor.execute("SELECT * FROM unknown_table")
except mysql.connector.Error as err:
    if err.errno == 1146:  # Table doesn't exist
        print("Error: Table not found.")
    else:
        print(err)

Error: Table not found.

Example 2: Handling Connection Errors

try:
    my_connect = mysql.connector.connect(host="localhost", user="root", passwd="wrong_password")
except mysql.connector.Error as err:
    if err.errno == 1045:  # Access denied
        print("Error: Access denied due to invalid credentials.")
    else:
        print(err)

Error: Access denied due to invalid credentials.

Example 3: Handling Database Not Found Error

try:
    my_connect = mysql.connector.connect(host="localhost", user="root", passwd="", database="nonexistent_db")
except mysql.connector.Error as err:
    if err.errno == 1049:  # Unknown database
        print("Error: Database not found.")
    else:
        print(err)

Error: Database not found.

Example 4: Handling Syntax Errors in SQL Queries

try:
    my_cursor.execute("SELCT * FROM students")  # Typo in SELECT
except mysql.connector.Error as err:
    if err.errno == 1064:  # SQL syntax error
        print("Error: SQL syntax error.")
    else:
        print(err)

Error: SQL syntax error.

Example 5: Handling Duplicate Entry Error

try:
    my_cursor.execute("INSERT INTO students (id, name) VALUES (1, 'John')")
except mysql.connector.Error as err:
    if err.errno == 1062:  # Duplicate entry
        print("Error: Duplicate entry for primary key.")
    else:
        print(err)

Error: Duplicate entry for primary key.

Example 6: Handling Foreign Key Constraint Failure

try:
    my_cursor.execute("INSERT INTO orders (customer_id, order_total) VALUES (999, 250)")
except mysql.connector.Error as err:
    if err.errno == 1452:  # Foreign key constraint fails
        print("Error: Foreign key constraint violation.")
    else:
        print(err)

Error: Foreign key constraint violation.

Example 7: Handling Connection Timeout

try:
    my_connect = mysql.connector.connect(host="localhost", user="root", passwd="", database="my_tutorial", connect_timeout=1)
except mysql.connector.Error as err:
    if err.errno == 2003:  # Connection timeout error
        print("Error: Connection timeout.")
    else:
        print(err)

Error: Connection timeout.

Example 8: Handling Invalid Hostname

try:
    my_connect = mysql.connector.connect(host="invalid_host", user="root", passwd="")
except mysql.connector.Error as err:
    if err.errno == 2005:  # Unknown MySQL server host
        print("Error: Unknown MySQL server host.")
    else:
        print(err)

Error: Unknown MySQL server host.

Subhendu Mohapatra

Author

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