Simple Tablespace: Can contain one or more tables Rows from multiple tables can be interleaved on a page under the DBAs control and maintenance.
Segmented Tablespace:Can contain one or more tables Tablespace is divided into segments of 4 to 64 pages in increments of 4 pages. Each segment is dedicated to single table. A table can occupy multiple segments.
Partitioned Tablespace:Can contain one table Tablespace is divided into parts and each part is put in a separate VSAM dataset.
One divided by the number of distinct values of a column.
Synonym is an alternate name for a table or view used mainly to hide the leading Qualifier of a table or view A synonym is accessible only by the creator.
SYNONYM: is dropped when the table or table space is dropped Synonym is available only to the creator ALIAS: is retained even if table or table space is dropped ALIAS can be created even if the table does not exist It is used mainly in distributed environment to hide the location info from programs Alias is a global object & is available to all.
This column cannot have nulls and while insertion, if no value is supplied then it wil have zeroes, spaces or date/time depending on whether it is numeric, character or date/time Use it when you do not want to have nulls but at the same time cannot give values all the time you insert this row.