Group by controls the presentation of the rows, order by controls the presentation of the columns for the results of the SELECT statement.
Latest Answer : Group By forms Groups (of course), but this means it also SORTS; but it will also retrieve a DISTINCT RECORD SETORDER BY Sorts by the columns included in the Statement, and does not retrieve DISTINCT Records.Neither determines the order of the columns ...
DB2 use the multiple indexes to satisfy multiple predicates in a SELECT statement that are joined by an AND or OR.
Primary key and foreign key columns; columns that have unique values; columns that have aggregates computed frequently and columns used to test the existence of a value.
A multiple index is not one index but two indexes for two different columns of a table. A composite index is one index made up of combined values from two columns in a table. If two columns in a table
Latest Answer : if an index is created on more than one column ,which r frequently used in where clause of select statement. it will show the effect in increace in performance . ...
For a clustered index DB2 maintains rows in the same sequence as the columns in the index for as long as there is free space. DB2 can then process that table in that order efficiently.
Latest Answer : Clustered index is unique for any given table and we can have only one clustered index on a table. The leaf level of a clustered index is the actual data and the data is resorted in case of clustered index ...
Latest Answer : i think only one clustering index ll be created for any table in DB2. This clustering index is created on the primary key of the table. for all other index(es) created on the table they ll be nonclustering index(es) . ...
Latest Answer : To answer the original question, for many releases only one column could appear in the result table of a subquery. As of Version 7 of DB2 the result of a subquery is equivalent to a fullselect which means that 750 columns can appear. ...
How to retrieve n-th row ie n-th record of any table irrespective of the columns and the values present in the table without using ROWID(As it is not supported in DB@)?
How do I see the table definitions (columns, data types of columns, constraints or default values set etc) of a table in QMF? I tried 'DESCRIBE TABLE' but didn't work (not able to execute in QMF). I can see the DCLGEN but looking for a way to see the actual table definition?
Latest Answer : Search for the table name in the DB2 table SYSIBM.SYSINDEXESSELECT * FROM SYSIBM.SYSINDEXES WHERE NAME = 'tablename' OR CREATOR = 'creator name' ; ...
