Solution Guide for Migrating Oracle on UNIX to SQL Server - Willy .Net

206 Developing: Applications — <strong>Migrating</strong> <strong>Oracle</strong> SQL and PL/SQLrow fetched is fetched. If n is 0, the same row is fetched again. It also allowsretrieving one row or block of rows from the current position in the result set.It supports data modifications to the rows at the current position in the result set.Step 4: Subprograms ConversionThe next step is to migrate the procedures, functions, and triggers. This sectiondiscusses how each component can be converted <strong>for</strong> use with SQL Server.<strong>Migrating</strong> ProceduresA stored procedure is a precompiled object. This means that a procedure is compiledbe<strong>for</strong>ehand and is readily available <strong>for</strong> the various applications to execute. As a result,time is not wasted parsing and compiling the procedure again. However, the procedurewill be compiled every time if it contains dynamic SQL. Stored procedures in SQL Serverare very similar to procedures in <strong>Oracle</strong> PL/SQL. Some similarities include:● Both can accept parameters and return multiple values in the <strong>for</strong>m of outputparameters (OUT parameter) to the calling procedure.● Both contain programming statements that per<strong>for</strong>m operations in the database,including calling other procedures.● Both can overwrite existing procedures. <strong>Oracle</strong> uses the keyword REPLACE, whileSQL Server uses ALTER.The syntax between <strong>Oracle</strong> and SQL Server procedures differs. The differences areshown in the following examples:● <strong>Oracle</strong>●CREATE OR REPLACE PROCEDURE (PARAMETER1 DATATYPE [IN OUT],PARAMETER2 DATATYPE [IN OUT],)ISVARIABLE1 DATATYPE;VARIABLE2 DATATYPE;BEGINEXECUTABLE STATEMENTS;EXCEPTIONEXECUTABLE STATEMENTS;END;SQL ServerCREATE PROCEDURE [ ; number ][ { @PARAMETER DATATYPE }[ VARYING ] [ = default ] [ OUTPUT ]] [ ,...n ] ASEXECUTABLE STATEMENTSIn the following example, a stored procedure calculates the number of months remaininguntil retirement <strong>for</strong> each employee. Retirement age is passed as a parameter to theprocedure. The output needs to be written into a table named RETIRE. The RETIREtable has two columns. The columns are EMPLOYEEID and MONTHS_REMAINING.The number of months remaining is calculated and inserted into this table. Be<strong>for</strong>e startingthe operation, the table needs to be flushed.● <strong>Oracle</strong>