Composite data types_ PL/SQL table

Composite data types PL/SQL provides three composite data types : TABLE, ROCORD, and VARRAY. Objects of type TABLE are called PL/SQL tables,which are modeled as database tables. PL/SQL tables use a primary key as array access to rows. The size of a PL/SQL is un constrained, i.e, the table size grows as new rows are added. PL/SQL tables can have one column and a primary key, neither of these can named. The column can have any data type, but the primary key must be of the type BINARY_INTEGER. You can visualize a PL/SQL to be a single dimension vertical array, which can hold unlimited elements

Declaring PL/SQL Declaration of PL/SQL tables is done in two steps : 1.Define a TYPE. 2.Declare PL/SQL tables of that type. TABLE types can be defined in the declarative part of any block, subprogram, or package using following syntax : TYPE IS TABLE OF {column type | varible datatype} [not null] INDEX BY BINARY _INTERGER;

The clause INDEX BY BINARY_INTEGER is a mandatory feature of the PL/SQL table declaration. A PL/SQL table of the type defined can be declared in the following way : ; For example, in the declarion section a type of PL/SQL table can be defined as follows: TYPE nametabtyp IS TABLE OF CHAR(10) INDEX BY BINARY_INTEGER; Now PL/SQL tables of the type nametabtyp can be declared as follows: Name_tab nametabtyp;

Referencing PL/SQL tables To reference rows in a PL/SQL table, a primary key value has to be specified using the following array _ like syntax : (index_subscript) For example, to reference rows in PL/SQL table name_tab, you would use: name_tab(3); To assign the value of a PL/SQL expression to a specific row you can use the following syntax : (index_subscript):=plsql_ expression; Example: name_tab(5):=‘MICKY’;

Composite data types _ PL/SQL RECORD types Objects of type RECORD are called records. Unlike PL/SQL tables, records have uniquely name fields, which can belong to different data types.

DECLARE TYPE nametabtyp IS TABLE OF CHAR(10) INDEX BY BINARY_INTEGER; Name_tab nametabtyp; BEGIN Num:=1; LOOP Name_table (num) :=‘Mikey’; num:= num+1; Exit when num >5 ; END LOOP; FOR i IN 1..5 LOOP DBMS_OUTPUT.PUT_LINE(‘Name’|| I ||’:’|| name_tab(i)); END LOOP; END; /

Declaring Records Like PL/SQL tables, records must be declared in two steps: 1.Define the RECORD type. 2.Declare user_defined records of that type. The RECORD type can be declared in the declarative part of any block, subprogram, or package using the following syntax: TYPE typename IS RECORD (fieldname1 { fieldtype | variable%TYPE | table.column%TYPE| table%ROWTYPE} [not null], ………. …….. fieldnameN { fieldtype | variable%TYPE | table.column%TYPE| table%ROWTYPE} [not null]); The %TYPE and %ROWTYPE attribute can be used to specify a field data type.

Example For example, to store the values of route_code and the fares as a structure, a type of record can be declared as follows: DECLARE TYPE route_rec_typ IS RECORD (route_code varchar2(7) NOT NULL :=‘SAN_LOU’; First_fare fare.first_fare%TYPE, Bus_fare fare.bus_fare%TYPE, Eco_fare fare.eco_fare%TYPE);

Note that the field declarations are like a variable declaration. Each field has a unique name and specific data type. The NOT NULL constraint can be added to any field declaration, provided they are initialized. In the above example, once type route_rec_typ is defined, records can be declared of that type as follows : Route_rec route_rec_typ;

Unlike PL/SQL tables, a record can be intialized in its declaration as shown below: DECLARE TYPE timetyp IS RECORD (second SMALLINT := 0, Minute SMALLINT:= 0, Hour SMALLINT := 0);

Referncing Records To reference individual field in a record, dot notation and the following syntax are to be used: Record_name. field_name; Instead of assigning values separately to each field in a record, values can be assigned to all field at once.This can be done in two ways. First, assign one record to another if they belong to the same datatype. DECLARE TYPE route_rec_typ IS RECORD(…..); Route_rec1 route_rec_typ; Route_rec2 route_rec_typ; …………. The following assignment is legal. BEGIN Route_rec1:= route_rec2;

Second, a list of column values can be assigned to a record by using the SELECT or FETCH statement. Just make sure the column names appear in the same order as the fields in the record. BEGIN SELECT route_code, first_fare, bus_fare, eco_fare INTO route_rec1 From fare Where route_code= ‘SAN_LOU’; ……… END; FETCH(تستخدم مع ال cursor )

Nested records PL/SQL allows for declaration and reference of nested records. A record can be the component of another record. For example:

DECLARE TYPE timetyp IS RECORD (minute SMALLINT, Hour SMALLINT); TYPE meetingtyp IS RECORD (day date, Time timetyp, -- nested record Place CHAR(20), Purpose CHAR(50)); TYPE partytyp IS RECORD (Day DATE, Time timetyp, -- nested record Bus_fare CHAR(15)); Meeting MEETINGTYP; Seminar MEETINGTYP; Party PARTYTYP; …… BEGIN Meeting.day:=’26-JUN-91’; Meeting.time.minute:=45; Meeting.time.hour:=10; …… END;

PL/SQL allows for an assignment of one nested record to another belonging to the same data type. For example : Seminar.time:= meeting.time; PL/SQL also allows for an assignment of one nested record to another if the containing records belong to different data types For example : Party.time:= meeting.time ;