Store XML Data in a Table in Oracle

Problem Statement:

You need to store native XML data into a relational table in your database.

Solution:

Oracle have several ways of storing XML documents. One way of storing data where our XML doesn’t need to be altered, or where a portion of the XML can be extracted with XSLT, is to use XMLTYPE data casting.

We will use the XMLTYPE call to cast the text provided into the XMLTYPE datatype. In the background Oracle XMLTYPE supports CLOB datatype, because XML is stored internally as a CLOB. This means we can use the same approach to casting, passing the call to XMLTYPE a string up to 4GB in size.

Casting to XMLTYPE enforces some rules for our XML data. If the column or a table is defined using an XML schema, the schema will be used to validate the data, ensuring that mandatory elements are present and the overall structure maps exactly to the schema.

We will first create a table to store the XML.

CREATE TABLE tmp_store_xml (result XMLTYPE);

Code

DECLARE
  result XMLTYPE;
    data VARCHAR2(10);
BEGIN
      FOR CUR IN (SELECT department_id FROM departments)
      LOOP
          WITH tmp AS
            (SELECT XMLROOT(XMLFOREST( dept_t(department_id, department_name,
                    CAST(MULTISET
                        (SELECT student_id,
                                first_name,
                                last_name,
                                phone_number
                           FROM students e
                          WHERE e.department_id = d.department_id
                        ) AS stulist_t
                        )) AS "Department"),version '1.0') AS dataxml
                FROM departments d
               WHERE d.department_id = '' || cur.department_id || ''
             )
       
        SELECT XMLTYPE.CREATEXML(XMLSERIALIZE(CONTENT (dataxml) INDENT size=2))
               INTO result
          FROM tmp;
         
        INSERT INTO tmp_store_xml VALUES(result);
        COMMIT;
      END LOOP;
END;

Output: One of the row from the table

<Department DEPTNO="60">
  <DNAME>IT</DNAME>
  <STU_LIST>
    <STU_T STUNO="103">
      <FNAME>BROWN</FNAME>
      <LNAME>MICHAEL</LNAME>
      <PHONE>111.111.1248</PHONE>
    </STU_T>
    <STU_T STUNO="104">
      <FNAME>JONES</FNAME>
      <LNAME>WILLIAM</LNAME>
      <PHONE>111.111.1249</PHONE>
    </STU_T>
    <STU_T STUNO="105">
      <FNAME>MILLER</FNAME>
      <LNAME>DAVID</LNAME>
      <PHONE>111.111.1250</PHONE>
    </STU_T>
    <STU_T STUNO="106">
      <FNAME>DAVIS</FNAME>
      <LNAME>RICHARD</LNAME>
      <PHONE>111.111.1251</PHONE>
    </STU_T>
    <STU_T STUNO="107">
      <FNAME>GARCIA</FNAME>
      <LNAME>CHARLES</LNAME>
      <PHONE>111.111.1252</PHONE>
    </STU_T>
  </STU_LIST>
</Department>

Data Preparation: Data used for the problem is shown below. The data is completely made up for demonstration purpose.

Example

DROP TABLE students;
COMMIT;

CREATE TABLE students
    ( student_id     NUMBER(6)
    , first_name     VARCHAR2(20)
    , last_name      VARCHAR2(25)
    , email          VARCHAR2(40)
    , phone_number   VARCHAR2(20)
    , join_date      DATE
    , class_id       VARCHAR2(20)  
    , fees           NUMBER(8,2)
    , professor_id   NUMBER(6)
    , department_id  NUMBER(4)
    ) ;

Example

CREATE UNIQUE INDEX stu_id_pk ON students (student_id) ;
INSERT INTO students VALUES (100,'SMITH','JAMES','[email protected]','111.111.1245',TO_DATE('17-06-2003','DD-MM-YYYY'),'INS_CHAIRMAN',24000,NULL,NULL);
INSERT INTO students VALUES (101,'JOHNSON','JOHN','[email protected]','111.111.1246',TO_DATE('21-09-2005','DD-MM-YYYY'),'INS_VP',17000,100,90);
INSERT INTO students VALUES (102,'WILLIAMS','ROBERT','[email protected]','111.111.1247',TO_DATE('13-01-2001','DD-MM-YYYY'),'INS_VP',17000,100,90);
INSERT INTO students VALUES (103,'BROWN','MICHAEL','[email protected]','111.111.1248',TO_DATE('03-01-2006','DD-MM-YYYY'),'INS_STAFF',9000,102,60);
INSERT INTO students VALUES (104,'JONES','WILLIAM','[email protected]','111.111.1249',TO_DATE('21-05-2007','DD-MM-YYYY'),'INS_STAFF',6000,103,60);
INSERT INTO students VALUES (105,'MILLER','DAVID','[email protected]','111.111.1250',TO_DATE('25-06-2005','DD-MM-YYYY'),'INS_STAFF',4800,103,60);
INSERT INTO students VALUES (106,'DAVIS','RICHARD','[email protected]','111.111.1251',TO_DATE('05-02-2006','DD-MM-YYYY'),'INS_STAFF',4800,103,60);
INSERT INTO students VALUES (107,'GARCIA','CHARLES','[email protected]','111.111.1252',TO_DATE('07-02-2007','DD-MM-YYYY'),'INS_STAFF',4200,103,60);
INSERT INTO students VALUES (108,'RODRIGUEZ','JOSEPH','[email protected]','111.111.1253',TO_DATE('17-08-2002','DD-MM-YYYY'),'CL_PHY',12008,101,100);
INSERT INTO students VALUES (109,'WILSON','THOMAS','[email protected]','111.111.1254',TO_DATE('16-08-2002','DD-MM-YYYY'),'CL_MATH',9000,108,100);
INSERT INTO students VALUES (110,'MARTINEZ','CHRISTOPHER','[email protected]','111.111.1255',TO_DATE('28-09-2005','DD-MM-YYYY'),'CL_MATH',8200,108,100);
INSERT INTO students VALUES (111,'ANDERSON','DANIEL','[email protected]','111.111.1256',TO_DATE('30-09-2005','DD-MM-YYYY'),'CL_MATH',7700,108,100);
INSERT INTO students VALUES (112,'TAYLOR','PAUL','[email protected]','111.111.1257',TO_DATE('07-03-2006','DD-MM-YYYY'),'CL_MATH',7800,108,100);
INSERT INTO students VALUES (113,'THOMAS','MARK','[email protected]','111.111.1258',TO_DATE('07-12-2007','DD-MM-YYYY'),'CL_MATH',6900,108,100);

COMMIT;

Example

CREATE TABLE departments
    ( department_id    NUMBER(4)
    , department_name  VARCHAR2(30)
    CONSTRAINT  dept_name_nn  NOT NULL
    , professor_id       NUMBER(6)
    , location_id      NUMBER(4)
    ) ;

Example

INSERT INTO departments VALUES ( 10, 'Administration', 200, 1700);
INSERT INTO departments VALUES ( 20, 'Teaching', 201, 1800);                            
INSERT INTO departments VALUES ( 30  , 'Purchasing'  , 114   , 1700 );
INSERT INTO departments VALUES ( 40  , 'Human Resources'  , 203  , 2400  );
INSERT INTO departments VALUES ( 50  , 'Students'  , 121  , 1500  );
INSERT INTO departments VALUES ( 60   , 'IT'  , 103  , 1400  );
INSERT INTO departments VALUES ( 70   , 'Public Relations'  , 204  , 2700  );
INSERT INTO departments VALUES ( 80   , 'Fee collectors'  , 145  , 2500  );  
INSERT INTO departments VALUES ( 90   , 'Executive'  , 100  , 1700  );
INSERT INTO departments VALUES ( 100   , 'Finance'  , 108  , 1700  );  
INSERT INTO departments VALUES ( 110   , 'Accounting'  , 205  , 1700  );
INSERT INTO departments VALUES ( 120   , 'Treasury'  , NULL  , 1700  );
INSERT INTO departments VALUES ( 130   , 'Corporate Tax'  , NULL  , 1700  );
INSERT INTO departments VALUES ( 140   , 'Control And Credit'  , NULL  , 1700  );
INSERT INTO departments VALUES ( 160   , 'Benefits'  , NULL  , 1700  );
INSERT INTO departments VALUES ( 230   , 'Helpdesk'  , NULL  , 1700  );
COMMIT;