Why Does My Yii Application Throw a 'SQLSTATE[HY093]: Invalid parameter number' Error When Using Multiple Databases?

"SQLSTATE[HY093]: Invalid parameter number: parameter was not defined" Error in Yii

When working with multiple databases in a Yii application, handling database-specific queries using Yii's DAO may encounter the error "SQLSTATE[HY093]: Invalid parameter number: parameter was not defined". This cryptic error can be frustrating to resolve without understanding the underlying cause.

The root of this error often lies in a misunderstanding of how parameters are declared and bound in the SQL statement. In Yii, the parameter placeholder in the SQL statement must exactly match the parameter key used in bindValue(). For instance, if the SQL statement specifies ":username" as a parameter, the bindValue() method should use the same parameter name, ":username".

In the provided code, the SQL statement includes the parameter ":username," but the bindValue() method uses ":alias". This discrepancy leads to the error because Yii cannot find ":username" in the SQL statement to bind the value to.

Additional potential causes of this error include:

• Omitting to include the bindValue() method for a parameter altogether.
• Invalid characters in the parameter placeholder name.
• Conflicts with CDataProvider pagination or sorting, especially when using complex joins.

To troubleshoot this issue, enabling parameter logging in the Yii config file can be invaluable. Enabling this feature will output the query and parameters involved in the error, aiding in identifying the cause. Additionally, carefully checking for any typos or mismatches in parameter names and ensuring all necessary parameters have been bound correctly will prevent this error from occurring.

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