COMPOSITE INDEX

Composite index is also a part of indexes which is used to create index on multiple columns (It allows maximum 32 columns).

Columns in a composite index can appear in any order and need not be adjacent columns of the table.

It will not create any constraints like unique.

Syntax:-

SQL>create index  on  (, ….column n);

Example:-

SQL> create index na_comp_idx on EMP (hiredate, sal);

-- Index created.

For dropping index

Syntax:-

Drop index ;

Example:-

SQL>Drop index idx1;

-- Index dropped

If we want drop index we can drop only one at a time but not multiple.

If we try to drop multiple indexes. System will raise an error like “sql command not properly ended “shown below.

SQL>drop index na_comp_idx, NA_UNIQ_CONS;