Datu bāzes lietotājs (user) un tā shēma (schema)

1

Relāciju datu bāzes struktūras (relational database structures)

1. Tabula (table)2. Tabulu klāsteris (table cluster)3. Tabula ar indeksa organizāciju (index-organized table)4. Ārējās tabulas (external table)5. Skats (view)6. Indekss (index)7. Virkne (sequence)8. Sinonīms (synonym)9. Dimensija (dimension)10. Materializēts skats (materialized view)

Datu bāzes lietotāju shēmas1. lietotāja shēma

2. lietotāja shēma

2

Piemēra shēma HR

3

Tabulu definējumu piemēriCREATE TABLE employees(employee_id NUMBER(6),first_name VARCHAR2(20),last_name VARCHAR2(25) CONSTRAINT emp_last_name_nn NOT NULL,email VARCHAR2(25) CONSTRAINT emp_email_nn NOT NULL,phone_number VARCHAR2(20),hire_date DATE CONSTRAINT emp_hire_date_nn NOT NULL,job_id VARCHAR2(10) CONSTRAINT emp_job_nn NOT NULL,salary NUMBER(8,2),commission_pct NUMBER(2,2),manager_id NUMBER(6),department_id NUMBER(4) , CONSTRAINT emp_salary_min CHECK (salary > 0),CONSTRAINT emp_email_uk UNIQUE (email) ) ;

ALTER TABLE employees ADD (CONSTRAINT emp_emp_id_pk RIMARY KEY (employee_id),CONSTRAINT emp_dept_fk FOREIGN KEY (department_id) REFERENCES departments,CONSTRAINT emp_job_fk FOREIGN KEY (job_id) REFERENCES jobs (job_id),CONSTRAINT emp_manager_fk FOREIGN KEY (manager_id) REFERENCES employees ) ;

4

Ārējā tabula (external table)

5

Tabulu klāsteri (clustered tables)

6

Indeksa struktūra (index structure)

7

Tabula ar indeksa organizāciju (index-organized table)

8

Skats (view)

CREATE VIEW staff_dept_10 ASSELECT employee_id, last_name, job_id, manager_id, department_idFROM employeesWHERE department_id = 10WITH CHECK OPTION CONSTRAINT staff_dept_10_cnst;

9

Materializētais skats (materialized view)

CREATE MATERIALIZED VIEW sales_mv AS SELECT t.calendar_year, p.prod_id, SUM(s.amount_sold) AS sum_sales FROM times t, products p, sales s WHERE t.time_id = s.time_id AND p.prod_id = s.prod_id GROUP BY t.calendar_year, p.prod_id;

10

SELECT vaicājuma pārrakstīšana lietojot materializētos skatus (query rewrite)

11

Datu vārdnīca (data dictionary)

Prefix User Access Contents NotesDBA_ Database

administratorsAll objects Some DBA_ views have additional columns

containing information useful to the administrator.

ALL_ All users Objects to which user has privileges

Includes objects owned by user. These views obey the current set of enabled roles.

USER_ All users Objects owned by user

Views with the prefix USER_ usually exclude the column OWNER. This column is implied in the USER_ views to be the user issuing the query.

12

Tabula DUAL

SQL> SELECT ((3*4)+5)/3 FROM DUAL; ((3*4)+5)/3----------- 5.66666667

13

Dināmiskie skati (dynamic performance views) System and session parameters Memory usage and allocation File states Progress of jobs and tasks SQL execution Statistics and metrics

14