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Objectives ,[object Object],[object Object],[object Object],[object Object],[object Object]

Database Objects Description Basic unit of storage; composed of rows and columns Logically represents subsets of data from one or more tables Generates primary key values Improves the performance of some queries Alternative name for an object Object Table View Sequence Index Synonym

What Is a Sequence? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The CREATE SEQUENCE Statement Syntax ,[object Object],[object Object],CREATE SEQUENCE sequence [INCREMENT BY n ] [START WITH n ] [{MAXVALUE n | NOMAXVALUE }] [{MINVALUE n | NOMINVALUE }] [{CYCLE | NOCYCLE }] [{CACHE n | NOCACHE}];

Creating a Sequence ,[object Object],[object Object],CREATE SEQUENCE dept_deptid_seq INCREMENT BY 10 START WITH 120 MAXVALUE 9999 NOCACHE NOCYCLE; Sequence created.

Confirming Sequences ,[object Object],[object Object],SELECT sequence_name, min_value, max_value, increment_by, last_number FROM user_sequences;

NEXTVAL and CURRVAL Pseudocolumns ,[object Object],[object Object],[object Object]

Using a Sequence ,[object Object],[object Object],INSERT INTO departments(department_id, department_name, location_id) VALUES (dept_deptid_seq.NEXTVAL, 'Support', 2500); 1 row created. SELECT dept_deptid_seq.CURRVAL FROM dual;

Using a Sequence ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Modifying a Sequence ,[object Object],ALTER SEQUENCE dept_deptid_seq INCREMENT BY 20 MAXVALUE 999999 NOCACHE NOCYCLE; Sequence altered.

Guidelines for Modifying a Sequence ,[object Object],[object Object],[object Object],[object Object]

Removing a Sequence ,[object Object],[object Object],DROP SEQUENCE dept_deptid_seq; Sequence dropped.

What is an Index? ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

How Are Indexes Created? ,[object Object],[object Object]

Creating an Index ,[object Object],[object Object],CREATE INDEX emp_last_name_idx ON employees(last_name); Index created. CREATE INDEX index ON table ( column [, column ]...);

When to Create an Index ,[object Object],[object Object],[object Object],[object Object],[object Object]

When Not to Create an Index ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Confirming Indexes ,[object Object],[object Object],SELECT ic.index_name, ic.column_name, ic.column_position col_pos,ix.uniqueness FROM user_indexes ix, user_ind_columns ic WHERE ic.index_name = ix.index_name AND ic.table_name = 'EMPLOYEES';

Function-Based Indexes ,[object Object],[object Object],CREATE INDEX upper_dept_name_idx ON departments(UPPER(department_name)); Index created. SELECT * FROM departments WHERE UPPER(department_name) = 'SALES';

Removing an Index ,[object Object],[object Object],[object Object],DROP INDEX upper_last_name_idx; Index dropped. DROP INDEX index ;

Synonyms ,[object Object],[object Object],[object Object],[object Object],CREATE [PUBLIC] SYNONYM synonym FOR object ;

Creating and Removing Synonyms ,[object Object],[object Object],CREATE SYNONYM d_sum FOR dept_sum_vu; Synonym Created. DROP SYNONYM d_sum; Synonym dropped.

Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Practice 12 Overview ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

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