Lesson 9
Managing tables and Schema Manager Conclusion
In this module, you learned to:
- Create a table
- Work with the basic Oracle datatypes
- Create a table using the Schema Manager
- Generate a list of the tables in your Oracle database
- Gather information about the columns in a table
- Modify a table by adding or modifying columns
- Delete a table
You can create a table based on a query without generating redo log entries (chronological records of database actions used during database recoveries). Avoiding the generation of these entries is accomplished by using the nologging keyword in the create table command. When the redo log entries are circumvented in this way, the performance of the create table command will improve because less work is being done; the larger the table, the greater the impact. However because the new table's creation is not being written to the redo log files (which record the redo log entries), the table will not be re-created if, following a database failure, those redo log files are used to recover the database.
Therefore, you should consider performing a backup of the database soon after using the nologging option if you want to be able to recover the new table.
The following example shows how to use the nologging keyword during table creations based on queries (by default, table creations based on queries generate redo log entries):
create table RAIN_NOLOG
nologging
as
select * from TROUBLE;
Table created. Note that you can specify nologging at the partition level and at the LOB level (see Chapters 18 and 40). The use of nologging will improve the performance of the operations that load the data in the table.
Glossary
In this module, you learned the following glossary terms:
- CASE: Computer Aided Software Design, a process where the implementation details of application systems are partially determined through computerized automation.
- Data Definition Language: The portion of the SQL language that is used to create and alter the structures that hold the data in the database.
- Data Dictionary: A group of tables and views that define the structures in a database.
- National Language Subset: A group of characters that are used to represent a specific national language or dialect.
- Oracle interMedia: An option for the Oracle database designed for handling specific types of large data (such as images or spatial data) and text.
- Schema: A structure in an Oracle database that contains database structures, typically owned by the schema owner.
The next module is about the various ways you can add constraints to tables and columns that limit the values of data that can be placed into the database.
Altering Dropping Tables - Quiz
