distributed database applications cosc 5050 week two

Distributed Database Applications

COSC 5050Week Two

Jiangping WangWebster University Distributed Database Applications

Outline

Data types and composite structuresWorking with program dataStringsNumbersDates and TimestampsRecords and CollectionsMiscellaneous datatypes


Program Data

Naming rulesUp to 30 charactersStart with a letterCan have letters, numerals, $, #, and _Case-insensitive


Oracle Predefined Datatypes

CHAR(n)

VARCHAR2(n)

NUMBER(n)

NUMBER(n, m)

PLS_INTEGER

BOOLEAN

DATE


Groups of Data TypesScalar types – predefined data types%TYPE attributes

Supports types that may be derived from a database table definitionInclude %TYPE and %ROWTYPE

Composite typesMay be created from TABLES and RECORDS

%ROWTYPEThese are composite types with a structure that is derived from a base table or a cursor declaration


Declaring Program DataVariable

l_total_count NUMBER;l_dollar_amount NUMBER (10, 2);l_right_now DATE NOT NULL DEFAULT SYSDATE;l_favorite_flavor VARCHAR2(100)

:= ‘Anything with chocolate, actually';TYPE list_of_books_t IS TABLE OF book%ROWTYPE INDEX BY BINARY_INTEGER;oreilly_oracle_books list_of_books_t;

Constantl_curr_year CONSTANT PLS_INTEGER := TO_NUMBER(TO_CHAR(SYSDATE, ‘YYYY’));

l_author CONSTANT VARCHAR2(100) DEFAULT ‘Bill Pribyl’;


Anchored DeclarationsScalar anchoring

Based on column or other scalar variable%TYPEl_company_id company.company_id%TYPEemp_id emp.empno%TYPEnew_emp emp_id%TYPE

Record anchoringBased on table or explicit cursor%ROWTYPEl_book book%ROWTYPE;l_employee employee%rowtype;l_employee emp_cur%rowtype;

Benefits of anchored declarations


Anchored Declarations

Column%TYPE

create or replace procedure charge is-- customer.account column is defined as number(7,2)balance customer.account%type;

beginbalance := 50.12;balance := balance * 1.12; -- what is the value?dbms_output.put_line('balance is : ' || balance);

end charge;/


Anchored Declarationsdeclare

l_employee employee%rowtype;begin

select * into l_employee from employeewhere ssn = '600000001';dbms_output.put_line(l_employee.fname || ' ' || l_employee.lname);

end;

declarecursor emp_cur is

select fname, lname from employeewhere ssn = '600000001';

l_employee emp_cur%rowtype;begin

open emp_cur;fetch emp_cur into l_employee;dbms_output.put_line(l_employee.fname || ' ' || l_employee.lname);close emp_cur;

end;


Programmer Defined Subtypes

Define subtypes or aliases of predefined datatypes

SUBTYPE subtype_name IS base_typeSUBTYPE POSITIVE IS BINARY_INTEGER

RANGE 1 .. 2147483647;

SUBTYPE FLOAT IS NUMBER;

SUBTYPE big_string IS VARCHAR2(32767);


Datatype Conversions

Implicit conversation vs. explicit conversion

Figure 7-2, page 184Implicit conversions

Table 7-1, page 185The built-in conversion functionsTO_CHAR( )

TO_NUMBER( )

TO_DATE( )

DECLARE a_number NUMBER; BEGIN a_number := '125'; END;


Implicit Conversation


StringsCHAR(n)

feature_name CHAR(100);

VARCHAR2(n)small_string VARCHAR2(4);

line_of_text VARCHAR2(2000);

Fixed-length Variable-length

Database character set CHAR VARCHAR2

National character set NCHAR NVARCHAR2

Jiangping Wang

PL/SQL subtypes and their equivalentsTable 8-1, page 194

Webster University Distributed Database Applications

String Subtypes

Subtype Equivalent PL/SQL type

CHAR VARYING VARCHAR2

CHARACTER CHAR

CHARACTER VARYING VARCHAR2

NATIONAL CHAR NCHAR

NATIONAL CHAR VARYING NVARCHAR2

NATIONAL CHARACTER NCHAR

NATIONAL CHARACTER VARYING NVARCHAR2

NCHAR VARYING NVARCHAR2

STRING VARCHAR2

VARCHAR VARCHAR2


Empty Strings are NULLDECLARE

empty_varchar2 VARCHAR2(10) := '';

empty_char CHAR(10) := '';

BEGIN

IF empty_varchar2 IS NULL THEN

DBMS_OUTPUT.PUT_LINE('empty_varchar2 is NULL');

END IF;

IF '' IS NULL THEN

DBMS_OUTPUT.PUT_LINE(''''' is NULL');

END IF;

IF empty_char IS NULL THEN

DBMS_OUTPUT.PUT_LINE('empty_char is NULL');

ELSIF empty_char IS NOT NULL THEN

DBMS_OUTPUT.PUT_LINE('empty_char is NOT NULL');

END IF;

END;

/


String ComparisonsDECLARE

company_name CHAR(30) := 'Feuerstein and Friends';

char_parent_company_name CHAR(35) := 'Feuerstein and Friends';

varchar2_parent_company_name VARCHAR2(35) := 'Feuerstein and Friends';

BEGIN

--Compare two CHARs, so blank-padding is used

IF company_name = char_parent_company_name THEN

DBMS_OUTPUT.PUT_LINE ('first comparison is TRUE');

ELSE

DBMS_OUTPUT.PUT_LINE ('first comparison is FALSE');

END IF;

--Compare a CHAR and a VARCHAR2, so nonblank-padding is used

IF company_name = varchar2_parent_company_name THEN

DBMS_OUTPUT.PUT_LINE ('second comparison is TRUE');

ELSE

DBMS_OUTPUT.PUT_LINE ('second comparison is FALSE');

END IF;

END;

/


String FunctionsASCII, CHR

CHR(64) -- which is ‘@’

INSTRDECLARE company_name VARCHAR2(30) := 'Microsoft Inc.';BEGIN DBMS_OUTPUT.PUT_LINE(INSTR (company_name, 'Inc'));END;

LENGTHLENGTH(‘abcd’) -> 4LENGTH(NULL) -> NULL

SUBSTR, LOWER, UPPER, INITCAPCONCAT

begin dbms_output.put_line('abc' || 'def' || 'ghi'); dbms_output.put_line(concat(concat('abc','def'),'ghi'));end;


NumbersNUMBER

NUMBER(precision, scale)NUMBER(9,2)NUMBER(9,11)NUMBER(9,-11)Rounding of values (page 234)

PLS_INTEGERUses native machine arithmetic

BINARY_INTEGEREquivalent to PLS_INTEGER (since 10g)Uses platform independent library code (before 10g)

Numeric subtypes (page 246)

Jiangping Wang

Numeric Subtypes



Numeric FunctionsTO_NUMBER

begin dbms_output.put_line(to_number('12345.67'));end;

TO_CHARDECLARE b VARCHAR2(30);BEGIN b := TO_CHAR(123456789.01,'L999G999G999D99'); DBMS_OUTPUT.PUT_LINE(b);END;

ABS, CEIL, FLOOR, POWER, SQRT


Date and TimeDATETIMESTAMP TIMESTAMP WITH TIME ZONE TIMESTAMP WITH LOCAL TIME ZONE

Jiangping Wang

Effect of different datetime datatypesFigure 10-1, page 269

Date and Time


Jiangping Wang

Comparison of functions that return current data and time

Table 10-1, page 272


Date and Time

Function Time zone Datatype returned

CURRENT_DATE Session DATE

CURRENT_TIMESTAMP Session TIMESTAMP WITH TIME ZONE

LOCALTIMESTAMP Session TIMESTAMP

SYSDATE Server DATE

SYSTIMESTAMP Server TIMESTAMP WITH TIME ZONE


Date and Time

DECLARE

today_date DATE := SYSDATE;

BEGIN

dbms_output.put_line(TO_CHAR(today_date));

END;

Format date and time

TO_DATE(’12/31/2003’); -- ?

TO_CHAR()

Jiangping Wang

Date/Time FormatTo display, the Date value is converted from the internal format to a printable stringOracle's default format for Date is

DD-MON-YY

To covert explicitlyTO_CHAR(value, 'MM/DD/YYYY')

Change the default Date format alter session set NLS_DATE_FORMAT='MM/DD/YYYY';


Jiangping Wang

Date/Time Format



TIMESTAMPTIMESTAMP datatypes

TIMESTAMP

DECLAREtoday_date TIMESTAMP := SYSDATE;

BEGINdbms_output.put_line(TO_CHAR(today_date));

END;

DECLAREthe_day date := to_date('22-MAR-2006');

BEGINdbms_output.put_line(the_day);

END;


Date/Time FunctionsADD_MONTHS functionBEGIN

dbms_output.put_line(add_months(sysdate, 3));dbms_output.put_line(add_months(sysdate, -3));

END;LAST_DAY functionDECLARE

the_day date := to_date('28-FEB-2010');BEGIN

dbms_output.put_line(last_day(the_day));dbms_output.put_line(last_day(sysdate));

END;MONTHS_BETWEEN functionDECLARE

the_day date := to_date('28-FEB-2010');BEGIN

dbms_output.put_line(months_between(sysdate, the_day));END;


Records

Records are composite structures

Similar to a row in a database table

Record allow you to select specific columns from one or more tables into single data structure


Declaring RecordsTable-based record

one_book books%rowtype;l_employee employee%rowtype;

Cursor-based recordcursor my_books_cur is select * from books where author like 'feuerstein%';one_sf_book my_books_cur%rowtype;

cursor emp_cur is select fname, lname from employee where ssn = '600000001';l_employee emp_cur%rowtype;


Declaring Records

Programmer-defined recordTYPE book_info_rt IS RECORD (

author books.author%TYPE,

category VARCHAR2(100),

total_page_count POSITIVE);

steven_as_author book_info_rt; -- not %ROWTYPE


Programmer-Defined Record

TYPE customer_sales_rectype IS RECORD

(customer_id NUMBER (5),

customer_name customer.name%TYPE,

total_sales NUMBER (15,2)

);

prev_customer_sales_rec customer_sales_rectype;

top_customer_rec customer_sales_rectype;


Working with RecordsDECLARE

TYPE customer_sales_rectype IS RECORD

(customer_id NUMBER (5),

customer_name customer.name%TYPE,

total_sales NUMBER (15,2)

);

top_customer_rec customer_sales_rectype;

BEGIN

SELECT customer_id, name, SUM(total_sales)

INTO top_customer_rec

FROM cust_sales_roundup

WHERE sold_on < ADD_MONTHS (SYSDATE, -3)

GROUP BY customer_id, name;

END;


Record-Level OperationsCopy contents of one record to anotherAssign a value of NULL to a record with a simple assignmentDefine and pass record as an argument in a parameter listRETURN a record back through the interface of a functionInsert into a database table with record

Since Oracle9i Database Release 2


Record-Level Operations

Cannot use the IS NULL syntax to see if all fields have NULL values

Apply IS NULL operator to each field individually

Cannot compare two recordsCompare each field individually


Field-Level OperationsDECLARE TYPE phone_rectype IS RECORD (area_code VARCHAR2(3), exchange VARCHAR2(3), phone_number VARCHAR2(4) ); TYPE contact_set_rectype IS RECORD (day_phone# phone_rectype, eve_phone# phone_rectype, fax_phone# phone_rectype );

auth_rep_info_rec contact_set_rectype; BEGIN ... auth_rep_info_rec.fax_phone#.area_code := auth_rep_info_rec.day_phone#.area_code; ...END;


Comparing Records

To test for record equality, each field has to be compared individuallyCompare for NULL(first_book.favorite_author = second_book.favorite_author

OR

(first_book.favorite_author IS NULL AND second_book.favorite_author IS NULL)


CollectionsA collection is a list of itemsOne dimensioned arrayDefine a particular structure using the TYPE statement – datatypeDeclare the actual collection based on the table typeTypes of collections

Associative arraysNested tablesVARRAYs

Jiangping Wang

CollectionsAssociative arrays

Single-dimensional, unbounded, sparse collections of homogeneous elementsPL/SQL only

Nested tablesSingle-dimensional, unbounded collections of homogeneous elementsCan be sparse

VARRAYsSingle-dimensional collections of homogeneous elementsalways bounded and never sparse



Collectionsdeclare

type list_of_dates_t is table of date;type list_of_names_t is table of varchar2(100)

index by pls_integer;birthdays list_of_dates_t := list_of_dates_t();happyfamily list_of_names_t;

beginbirthdays.extend;birthdays(1) := '23-sep-1958';birthdays.extend;birthdays(2) := '1-oct-1968';happyfamily(1) := 'Steven';happyfamily(2) := 'Veva';happyfamily(4) := 'Chris';happyfamily(5) := 'Eli';dbms_output.put_line(birthdays.count);dbms_output.put_line(happyfamily.first);

end;


CollectionsDECLARE

CURSOR emp_cur IS

SELECT * FROM employee;

TYPE emp_data_type IS TABLE OF emp_cur%ROWTYPE

INDEX BY PLS_INTEGER;

emp_table emp_data_type;

i pls_integer;

emp_id employee.ssn%type;

BEGIN

i := 1;

OPEN emp_cur;

LOOP

FETCH emp_cur INTO emp_table(i);

EXIT WHEN emp_cur%NOTFOUND;

dbms_output.put_line(emp_table(i).lname);

i := i + 1;

END LOOP;

CLOSE emp_cur;

dbms_output.put_line('Number of employee: ' || emp_table.count);

END;


Miscellaneous Datatypes

Boolean datatypeROWID and UROWIDLOB datatypeXMLType datatype


Boolean DatatypeDECLARE b BOOLEAN := FALSE;BEGIN IF b THEN dbms_output.put_line('true'); ELSE dbms_output.put_line('false'); END IF;END;/

Oracle RDBMS does not support a Boolean datatype


UROWID & ROWID Datatype

DECLARE employee_rowid urowid; emp_fname varchar2(20);BEGIN SELECT rowid, fname INTO employee_rowid, emp_fname FROM employee WHERE lname = 'Letterman'; dbms_output.put_line(employee_rowid); dbms_output.put_line(emp_fname);END;/


LOB Datatype

BFILEFile locator point to an operating system file outside the database

BLOB, CLOB, NCLOBLOB locator point to a large object stored inside the database


XMLType Datatype

Use XMLType to define database columns and PL/SQL variablesMethods defined on XMLType

Instantiate new XMLType valuesExtract portions of an XML documentManipulate the contents of an XML document


XMLType TypeCREATE TABLE falls ( fall_id NUMBER, fall XMLType);

INSERT INTO falls VALUES (1, XMLType.CreateXML( '<?xml version="1.0"?> <fall> <name>Munising Falls</name> <county>Alger</county> <state>MI</state> <url>http://michiganwaterfalls.com</url> </fall>'));

SELECT fall_id FROM falls f WHERE f.fall.existsNode('/fall/url') > 0;


HomeworkCreate an anonymous PL/SQL block to retrieve data from above database table into a record and display a detailed report of records.Create an anonymous PL/SQL block to retrieve data from above database table into a collection and display a detailed report of records.Create a simple procedure in DB2 to test if empty strings are null in IBM DB2.Lab activities

distributed database applications cosc 5050 week two

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