Use this statement to display a message.

Syntax

MESSAGE expression, ...
[ TYPE { INFO | ACTION | WARNING | STATUS } ]
[ TO { CONSOLE 
   | CLIENT [ FOR { CONNECTION conn-id [ IMMEDIATE ] | ALL } ] 
   | [ EVENT | SYSTEM ] LOG }
   [ DEBUG ONLY ] ]

conn-id : integer

Parameters

Remarks

The MESSAGE statement displays a message, which can be any expression. Clauses can specify the message type and where the message appears.

The procedure issuing a MESSAGE ... TO CLIENT statement must be associated with a connection.

For example, the window is not displayed in the following example because the event occurs outside a connection.

CREATE EVENT CheckIdleTime
TYPE ServerIdle
WHERE event_condition( 'IdleTime' ) > 100
HANDLER
BEGIN
   MESSAGE 'Idle engine' TYPE WARNING TO CLIENT;
END;

However, in the following example, the message is written to the database server messages window.

CREATE EVENT CheckIdleTime
TYPE ServerIdle
WHERE event_condition( 'IdleTime' ) > 100
HANDLER
BEGIN
   MESSAGE 'Idle engine' TYPE WARNING TO CONSOLE;
END;

Valid expressions can include a quoted string or other constant, variable, or function.

The FOR clause can be used to notify another application of an event detected on the database server without the need for the application to explicitly check for the event. When the FOR clause is used, recipients receive the message the next time that they execute a SQL statement. If the recipient is currently executing a SQL statement, the message is received when the statement completes. If the statement being executed is a stored procedure call, the message is received before the call is completed.

If an application requires notification within a short time after the message is sent and when the connection is not executing SQL statements, use the IMMEDIATE clause to implement client notification and not multiple concurrent WAITFOR DELAY statements.

Typically, messages sent using the IMMEDIATE clause are delivered in less than five seconds, even if the destination connection is not making database server requests. Message delivery could be delayed if the client connection makes several requests per second, receives very large BLOB data, or if the client's message callback executes for more than a second. In addition, sending more than one IMMEDIATE message to a single connection every two seconds could delay message delivery or generate an error message. If the client connection is disconnected, a successful MESSAGE ... IMMEDIATE statement may not be delivered.

Messages sent without the IMMEDIATE clause are only delivered when the client executes a specific request, or a WAITFOR DELAY statement. As a result, the delivery time of messages is unlimited.

The IMMEDIATE clause requires a SQL Anywhere version 11.0.1 or newer DBLib, ODBC or iAnywhere JDBC client library. The IMMEDIATE clause is not supported by non-threaded Unix client libraries. An error message is generated when a message is sent to a destination connection that does not support the IMMEDIATE clause.

A MESSAGE ... TO CLIENT expression can be truncated to 2048 bytes. For messages sent with the IMMEDIATE clause, the message expression can be truncated to the smaller of the packet size of the connection or 2048 bytes.

Embedded SQL and ODBC clients receive messages via message callback functions. In each case, these functions must be registered. In embedded SQL, the message callback is registered with db_register_a_callback using the DB_CALLBACK_MESSAGE parameter. In ODBC, the message callback is registered with SQLSetConnectAttr using the ASA_REGISTER_MESSAGE_CALLBACK parameter.

Permissions

DBA authority is required to execute a MESSAGE statement containing a FOR clause or a TO EVENT LOG or TO SYSTEM LOG clause.

Side effects

None.

See also

• CREATE PROCEDURE statement (web services)
• debug_messages option [database]
• db_register_a_callback function

Standards and compatibility

Example

The following procedure displays a message on the database server messages window:

CREATE PROCEDURE message_text()
BEGIN
MESSAGE 'The current date and time: ', Now();
END;

The following statement displays the string The current date and time, followed by the current date and time, in the database server messages window.

CALL message_text();