Oracle Advanced (ii) Oracle other database objects

1.Sequence

n automatically generates a unique number n is a shared object n A typical primary key applied to a table N Alternative application code N Place the serial number value in the cache to increase access speed

CREATE SEQUENCE Dept_deptno      by 1        with NOCACHE nocycle;          

2.Index

n is an object n use pointers to speed up record access n Reduce hard disk I/O n indexes exist independently of the table  N Database automatic use and maintenance Create an index rule The indexed column should be in a WHERE clause, or a join condition. This column has a wide range of domains. This column contains a large number of null values. A column that is often used together in a WHERE clause or join condition. The result of a large table query is less than the 2~4% of the total data

CREATE INDEX      emp_ename_idx  on             emp (ename);

4.function-based Index

CREATE INDEX Upper_dept_name_idx

On dept (UPPER (dname));

5. Synonyms

A synonym is another name for a database object for ease of use. Refer to another user's table. A shorter object name.

CREATE synonym    d_sum  for            dept_sum_vu; Synonym Created.

Oracle Advanced (ii) Oracle other database objects