QSqlError

QSqlError is a lightweight value object in the QtSql module that encapsulates information about a database error that occurred during a database operation. It is most commonly obtained from QSqlQuery::lastError() after executing a query, but drivers or higher-level components may also construct or propagate QSqlError objects. The class is intended to convey both machine-readable and human-readable error data to help diagnose issues in database access and SQL execution.

A QSqlError carries several pieces of information: the error type (QSqlErrorType), a native error number from the database driver (int), a driver-specific error message (driverText), and a database-specific error message (databaseText). A general, user-facing description can be retrieved with text(). The error type indicates categories such as NoError, ConnectionError, StatementError, or UnknownError.

Typical use is to check whether an operation succeeded by examining the error type or isValid(), and then inspecting the fields to determine the cause. For example, a non-NoError type suggests a problem during connection or statement execution. The messages can be logged or displayed to users, with driverText often including vendor-specific details and databaseText providing the database’s response.

QSqlError is part of the QtSql module and interoperates with QSqlQuery and QSqlDatabase. It is designed to be lightweight and copyable, allowing the error details to be passed through components that report or handle database issues.