The term “myth” refers to a principle which either was never true, or, used to be true, but is no longer. Most database myths originated as the result of changing technology.  Myths endure because they sound plausible.

The whole area of Database myths is an interesting one. One of the fascinations of working with databases is that, the more you learn, the more you realize you don't know. However, the more one discovers, the more one is obliged to admit that for many of the myths reality is different.

There are lots of variations on these myths. Many of these have been bunked out. Read down and see how many myths are you able to bunk.

1. OO databases can better store large, multimedia data.


2. OODBMS are overall faster than RDBMS


3. SQL is the best relational language


4. High-update tables and indexes rarely need reorganization.


5. DB/2 is the only viable database on MVS.


6. Oracle was developed on Unix and is therefore not optimized for OS/390.


7. Oracle can't do MOLAP.


8. DB2 only runs on mainframes.


9. SQL Server doesn't scale.


10. Oracle is eye-wateringly expensive.


11. Access isn't a relational database.


12. SQL Server cannot row lock.


13. “select count(1)” is faster than “select count(*)”, because enclosing a literal instead of the wildcard character prevents an expansion to include all columns, consuming more computing power, purportedly.


14. CHAR datatypes are more efficient to use than VARCHAR2 datatypes because CHAR are fixed-length and VARCHAR2 are variable-length. It takes less computing to process fixed-length data, as everyone knows, goes the reasoning.


15. All tables and indexes should be reorganized periodically to improve performance.


16. All tables and indexes perform best when everything is compressed into a single extent.


17. You must use a index, full tablescans are always less efficient and slower.


18. If you index each individual column the optimizer will use multiple indexes in a query if the predicate has any combination of the columns, so build a index on every column.


19. You must build a calculated column to properly index a date field. So to store a date, the best way to do it is with a VARCHAR field to improve DML to the table.


20. Oracle is an industry thought leader for Grid Computing.


21. Oracle Database 10g is Grid-enabled and is widely adopted.


22. Oracle's pricing adjustment will eliminate a major cost advantage for Microsoft SQL Server.


23. Oracle Database 10g is more secured than SQL Server 2000 and has more security certifications.


24. Oracle10g simplifies database management and increases database administrator productivity with smart self-tuning.


25. Oracle provides all the necessary enterprise security features built in, not bolted on, and has a long list of security certifications.


26. You can not create an union query with separate order by clauses.


27. You can not do a select on a stored procedure.


28. Basing an updateable recordset on a view means that you are updating the view from the recordset.


29. Truncate doesn't preserve the identity value but delete does


30. You can't truncate tables that are referenced by a foreign key constraint.


31. Truncate Cannot Be Rolled Back Because It Is Not Logged


32. The "shared-nothing" approach to database clustering in SQL Server 2000 is not viable and no customers are using it.


33. Bit fields can't contain nulls.


34. You can't sort on a bit field.


35. You can't have an index on an calculated field.


36. An mdf/ldf file is secure and can only be used on the server it was created on.


37. An update to a row in a table is immediately saved to disk.


38. SQL Server is always faster than JET.


39. MSDE 1.0 / SQL Server 2000 Desktop edition starts slowing after 5 or more user sessions.


40. TCP/IP is always the fastest protocol.


41. Query compilation is faster than execution time, so don't worry about plan reuse.


42. Query plans are executed immediately after compilation


43. The most cost-effective way to speed up SQL Server is to get a faster processor.


44. You can't update views that are composed of unions or contain order by clauses.


45. Views have their own execution plan. So, use a view when you want to reuse it's execution plan in multiple queries.


46. You cannot use a parameter in an order by clause.


47. You cannot perform cursor based updates to views from ADO in SQL Server 7.


48. SQL Server is the best relational database server in existence today.


49. Object-oriented approach and OODBMSs is superior to relational DBMS.


50. SQL Server is really a Sybase product not a Microsoft one.

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