Oracle data migration

First, if it is a large application and the data volume is indeed very large, we recommend that you use ORACLE directly. We do not recommend migrating data from SQL SERVER in the future,
Because the migration cost is very high (including the cost of downtime, testing, and risk of bugs ). For example, SQL SERVER to ORACLE. The main problems are as follows:
1. Data Type differences: although most data types are common, there are still exclusive data types, such as oracle log segment and ROWNUM.
These data types have their own special definitions (such as SEGMENT), and there are no corresponding concepts in other databases, so the conversion may be complicated.
2. Differences in Stored Procedures: SQL server uses T-SQL, while ORACLE uses PL/SQL, the two stored procedures, although similar syntax, but actually completely different.
Many functions of oracle pl/SQL are related to the features of ORACLE, and can be used without simple syntax similarity.
Therefore, rewriting of stored procedures is also a major problem.
3. Other problems: mainly include performance problems, SCHEMA attributes, and storage attributes. SQL Server migration: www.2cto.com oracle migration: Oracle provides free http://www.oracle.com/technetwork/products/migration/index-084442.html for database migration tools for different databases
Tutorial: http://st-curriculum.oracle.com/obe/db/hol08/sqldev_migration/mssqlserver
/Migrate_microsoft_sqlserver_otn.htm