Why Does My Python MySQL Code Throw a 'Not All Parameters Were Used in the SQL Statement' Error?

Not All Parameters Used in MySQL Statement: Troubleshooting in Python

Introduction

When executing SQL queries using Python and the mysql.connector library, it is crucial to align the parameter markers in the SQL statement with the data passed to the cursor. Failure to do so can result in the "Not all parameters were used in the SQL statement" error.

Error Encountered

Consider the following code snippet:

import mysql.connector

Name = "James"
Department = "Finance"
StartYear = 2001
CurrentPos = 2001
Link = ""

add_user = ("INSERT INTO DB.tbluser "
       "(username, department, startyear, currentpos, link) "
       "VALUES (%s, %s, %d, %d, %s)")
data_user = (Name, Department, StartYear, CurrentPos, Link)

Executing this code with the cursor.execute() method will trigger the "Not all parameters were used in the SQL statement" error.

Analysis

The error arises because the parameter marker for the StartYear and CurrentPos fields is incorrect. The %d marker is used for integers, while the SQL statement specifies %s markers for all parameters.

Solution

To resolve the error, the %d markers should be replaced with %s markers:

add_user = """INSERT INTO DB.tbluser 
              (username, department, startyear, currentpos, link) 
              VALUES (%s, %s, %s, %s, %s)"""

This change ensures that all parameters are properly represented in the SQL statement and can be correctly bound to the data passed to the cursor.

Note

Although the parameter markers in mysql.connector resemble the %s used in Python string formatting, the two syntaxes are distinct. Other database adapters may use different parameter markers, such as ? in oursql and sqlite3.

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