# Interacting with the database ## SQL operations _Create table:_ * If the given table does not exist, AxoSyslog tries to create it with the given column types. * The AxoSyslog application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges. * If AxoSyslog cannot create or alter a table, it tries to do it again when it reaches the next `time-reopen()`. _Alter table:_ * If the table structure is different from given structure in an existing table, AxoSyslog tries to add columns in this table but never will delete or modify an existing column. * If AxoSyslog cannot create or alter a table, it tries to do it again when reach the next `time-reopen()`. * The AxoSyslog application requires read and write access to the SQL table, otherwise it cannot verify that the destination table exists. _Insert table:_ * Insert new records in a table. * Inserting the records into the database is performed by a separate thread. * The AxoSyslog application automatically performs the escaping required to insert the messages into the database. * If insert returns with error, AxoSyslog tries to insert the message +two times by default, then drops it. Retrying time is the value of `time-reopen()`. ## Encoding The AxoSyslog application uses UTF-8 by default when writes logs into database. ## Start/stop and reload _Start:_ * The AxoSyslog application will connect to database automatically after starting regardless existing incoming messages. _Stop:_ * The AxoSyslog application will close the connection to database before shutting down. _Possibility of losing logs:_ * The AxoSyslog application cannot lose logs during shutting down if disk buffer was given and it is not full yet. * The AxoSyslog application cannot lose logs during shutting down if disk buffer was not given. _Reload:_ * The AxoSyslog application will close the connection to database if it received SIGHUP signal (reload). * It will reconnect to the database when it tries to send a new message to this database again. ## Macros: The value of ${SEQNUM} macro will be overridden by sql driver regardless of local or relayed incoming message. It will be grown continuously. * * * [MySQL-specific interaction methods](../../../docs/axosyslog-core/chapter-destinations/configuring-destinations-sql/sql-interactions-syslog-ng/mysql-specific-interaction-methods/index.md) [MsSQL-specific interaction methods](../../../docs/axosyslog-core/chapter-destinations/configuring-destinations-sql/sql-interactions-syslog-ng/mssql-specific-interaction-methods/index.md) Last modified June 27, 2023: [Moves content/docs to content/ to shorten output url (a5fcf1e)]()