Upgrade Guide - Prolifics

Database Interface" sm_d_msg_read—Reads messages from the default message file (SMMSGSvariable." sm_msg_read—Reads messages from a memory block." sm_msg_del—Deletes a message set from memory.The message classes have also been updated; FM_MSGS, JM_MSGS and JX_MSGSmessages are now located in SM_MSGS. The value for WB_MSGS has also been updated.Any instances of sm_msgread in a Panther application should be updated to the newmessage classes.Database InterfaceFor additional information, refer to page 1-27, “Database Interface API Changes.”Improved SQL ProcessingCurrently, DBMS SQL statements that specify data modification and do not returndata (INSERT, UPDATE, and DELETE statements) are executed by simply passing theSQL statement to the database immediately to process the statement quickly andefficiently. For SQL statements that return rows (SELECT), the process includes aprepare and execute cycle. This means that the database is first notified where to putthe data (if any), and then tells the database to execute the SQL.The method used to determine if a SQL statement returns rows is to execute the SQLstatement and see if it returns rows. If it does, it goes through the prepare and executecycle—essentially executing the SELECT statement twice. If the statement is a storedprocedure which inserts a row and then selects back data, the stored procedure isexecuted twice and therefore causes two copies of the row to be inserted.The new method of SQL statement processing includes two new DBMS statementswhich will improve SELECT-type processing and performance:" DBMS QUERY—Executes the SQL statement based on the assumption that itmay or may not return data.1-42 Upgrading to Panther from JAM 7