Managing Oracle Database Tables
A collection of 17 FAQs on database tables for DBA and developers. Clear answers are provided together with tutorial exercises to help beginners on creating, altering and removing tables, adding, altering and removing columns, and working with recycle bin.

Joining Tables
In our third Oracle DBA lesson we discuss joining tables together and joining tables to themselves.

Parallel Clause and Small Tables
If you have multiple CPUs available you may come up with the idea to set parallel execution on every table. The Oracle Optimizer should decide about the degree of parallelism or even if is necessary to use parallel execution at all. What's a great thing on big tables shows up badly on small ones. The split up of all the work over more than one CPU may result in an overhead which exceeds the execution time needed by one CPU by factors. While the Optimizer recognises for index accesses not to use parallel execution it doesn't for full table scans. This sounds reasonable at first hand but consider that often full table scans are the fastest option on smaller tables.

How to measure Index Selectivity
B*TREE Indexes improve the performance of queries that select a small percentage of rows from a table. As a general guideline, we should create indexes on tables that are often queried for less than 15% of the table's rows. This value may be higher in situations where all data can be retrieved from an index, or where the indexed columns can be used for joining to other tables.

Understanding SQL SELECT Query Statements
A collection of 33 FAQs on Oracle SQL SELECT query statements. Clear answers are provided with tutorial exercises on selecting rows and columns from tables and views, sorting and counting query outputs, grouping outputs and applying group functions, joining tables, using subqueries.

Loading and Exporting Data
A collection of 27 FAQs on Oracle loading data and exporting data. Clear answers are provided with tutorial exercises on saving data as flat files, loading data from flat, exporting and importing database, schema and tables, creating external tables.

Understanding SQL DML Statements
A collection of 15 FAQs on Oracle SQL DML statements. Clear answers are provided with tutorial exercises on inserting, updating and deleting rows from database tables.

Understanding SQL DDL Statements
A collection of 12 FAQs on Oracle SQL DDL statements. Clear answers are provided with tutorial exercises on creating, altering and dropping tables, indexes, and views.

How to specify the WHERE clause for UPDATE / DELETE
Sometimes multiple users are accessing the same tables at the same time. In these situations, you need to decide when to allow your application to update the database. If you allow your application to always update the database it could overwrite changes made by other users. You can control when updates succeed by specifying which columns are included in the WHERE clause of an UPDATE or DELETE statement.

N-Way Replication with New Oracle Streams book from Packt
N-Way replication takes the concepts for setting upa single-source configuration and applies it to a multi-master, or N-Way Replication environment configuration. Planning for N-Way replication starts with conflict resolution. Working with your business units is a must and setting and managing expectations needs to be done before any discussion of implementation. The use of Use Case scenarios driven down to transactions then to tables involved in those tansactions is one method to promote discussions with business units.

Managing Oracle User Accounts, Schema and Privileges
A collection of 23 FAQs on Oracle user account, schema and privileges. Clear answers are provided with tutorial exercises on creating user accounts, granting privileges for session connections, granting privileges for creating tables and inserting rows.