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

204 Developing: Applications — <strong>Migrating</strong> <strong>Oracle</strong> SQL and PL/SQL1. Declare Transact-SQL variables to contain the data returned by the cursor. Declareone variable <strong>for</strong> each result set column. Declare the variables to be large enoughto hold the values returned by the column.2. Associate a Transact-SQL cursor with a SELECT statement using the DECLARECURSOR statement. The DECLARE CURSOR statement also defines thecharacteristics of the cursor, such as the cursor name and whether the cursor isread-only or <strong>for</strong>ward-only.3. Use the OPEN statement to execute the SELECT statement and populate thecursor.4. Use the FETCH INTO statement to fetch individual rows and have the data <strong>for</strong>each column moved into a specified variable. Other Transact-SQL statements canthen reference those variables to access the fetched data values. Transact-SQLcursors do not support fetching blocks of rows.5. When you are finished with the cursor, use the CLOSE statement. Closing a cursorfrees some resources, such as the cursor's result set and its locks on the currentrow, but the cursor structure is still available <strong>for</strong> processing if you reissue an OPENstatement. Because the cursor is still present, you cannot reuse the cursor name atthis point. The DEALLOCATE statement completely frees all resources allocated tothe cursor, including the cursor name. After a cursor is de-allocated, you mustissue a DECLARE statement to rebuild the cursor.Th e cursor syntax differs between <strong>Oracle</strong> and SQL Server:● <strong>Oracle</strong>●DECLARECURSOR IS < SELECT STATEMENT>BEGINFOR IN CURSOR_NAMELOOP-- Business LogicEND LOOP;END;SQL ServerDECLARE DECLARE CURSOR FOR BEGINOPEN FETCH NEXT FROM INTO WHILE @@FETCH_STATUS = 0BEGIN-- business logic goes hereFETCH NEXT FROM INTO ENDCLOSE DEALLOCATE END<strong>Oracle</strong> allows the entire cursor record to be transferred into a user-defined data structuredefined using ROWTYPE. In SQL Server, the record values need to be assigned into anindividual variable. The following example uses ROWTYPE to process the SHIPPERStable record byrecord.