Oracle PL/SQL Tutorial/XML/Introduction

Create a table to hold the simple "Hello World" XML document

   <source lang="sql">

SQL> CREATE TABLE myTable

 2  (id  NUMBER PRIMARY KEY
 3  ,doc XMLType NOT NULL)
 4  XMLTYPE doc STORE AS CLOB
 5  /

Table created. SQL> SQL> SQL> SQL> DECLARE

 2      v_doc  XMLType;
 3      v_text varchar2(100);
 4  BEGIN
 5      select doc into v_doc from myTable
 6      where id = 2;
 7
 8      v_text := v_doc.extract("/message/body/text()" ).getstringval;
 9
10      dbms_output.put_line(v_text);
11  END;
12  /

SQL> SQL> drop table myTable; Table dropped. SQL></source>

Create table based on single data type

   <source lang="sql">

SQL> create table myTable of xmltype; Table created. SQL> SQL> insert into myTable values(XMLTYPE("

 2    <customer>
 3     <name>name value</name>
 4     <telephone>123 555-1234</telephone>
 5    </customer>"))
 6  /

1 row created. SQL> SQL> select * from myTable;

SYS_NC_ROWINFO$

---

 <customer>
  <name>name value</name>
  <telephone>123 555-1234</telephone>

1 row selected. SQL> SQL> SQL> drop table myTable; Table dropped.</source>

Create table myTable of xmltype

   <source lang="sql">

SQL> create table myTable of xmltype; Table created. SQL> SQL> insert into myTable values(XMLTYPE("

 2    <customer>
 3     <name>name value</name>
 4     <telephone>123 555-1234</telephone>
 5    </customer>"))
 6  /

1 row created. SQL> SQL> select * from myTable;

SYS_NC_ROWINFO$

---

 <customer>
  <name>name value</name>
  <telephone>123 555-1234</telephone>

1 row selected. SQL> SQL> SQL> drop table myTable; Table dropped.</source>

SQL to XML

Generating XML from "Ordinary" Tables

Oracle provides a function, XMLElement, that transforms data into XML format.

The function takes two arguments ?a the tag name and the data. Consider this example:

   <source lang="sql">

SQL> -- create demo table SQL> create table Employee(

 2    ID                 VARCHAR2(4 BYTE)         NOT NULL,
 3    First_Name         VARCHAR2(10 BYTE),
 4    Last_Name          VARCHAR2(10 BYTE),
 5    Start_Date         DATE,
 6    End_Date           DATE,
 7    Salary             Number(8,2),
 8    City               VARCHAR2(10 BYTE),
 9    Description        VARCHAR2(15 BYTE)
10  )
11  /

Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2               values ("01","Jason",    "Martin",  to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto",  "Programmer")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("02","Alison",   "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("03","James",    "Smith",   to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("04","Celia",    "Rice",    to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("05","Robert",   "Black",   to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("06","Linda",    "Green",   to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York",  "Tester")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("07","David",    "Larry",   to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York",  "Manager")
 3  /

1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)

 2                values("08","James",    "Cat",     to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
 3  /

1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee

 2  /

ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION

---

-------------------- -------------------- --------- --------- ---------- ---------- ---------------

01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT xmlelement("Name",first_name), xmlelement("ID",id),

 2    xmlelement("City", city)
 3  FROM employee;

XMLELEMENT("NAME",FIRST_NAME) XMLELEMENT("ID",ID) XMLELEMENT("CITY",CITY)

---

<Name>Jason</Name> <ID>01</ID> <City>Toronto</City> <Name>Alison</Name> <ID>02</ID> <City>Vancouver</City> <Name>James</Name> <ID>03</ID> <City>Vancouver</City> <Name>Celia</Name> <ID>04</ID> <City>Vancouver</City> <Name>Robert</Name> <ID>05</ID> <City>Vancouver</City> <Name>Linda</Name> <ID>06</ID> <City>New York</City> <Name>David</Name> <ID>07</ID> <City>New York</City> <Name>James</Name> <ID>08</ID> <City>Vancouver</City>

8 rows selected. SQL> SQL> SQL> -- clean the table SQL> drop table Employee

 2  /

Table dropped. SQL> SQL></source>

Use Aggregrate functions on XML data

   <source lang="sql">

SQL> CREATE TABLE myTable

 2    (myID            NUMBER PRIMARY KEY,
 3     myValue     XMLTYPE )
 4     XMLTYPE myValue STORE AS CLOB
 5  /

Table created.

SQL> SQL> SQL> select count(extract(myValue,"/ROWSET") )

 2         AS count
 3  from myTable;
    COUNT

---

        0

1 row selected. SQL> SQL> SQL> drop table myTable; Table dropped. SQL></source>

Use Text() function to get text value from xml string

   <source lang="sql">

SQL> CREATE TABLE myTable(

 2      id  NUMBER PRIMARY KEY,
 3      emps XMLType NOT NULL
 4  );

Table created. SQL> SQL> INSERT INTO myTable VALUES (1, xmltype("<?xml version="1.0" standalone="no"

?>
 2  <emps>
 3      <emp>
 4          <home_address>address 1</home_address>
 5      </emp>
 6  </emps>")
 7  );

1 row created. SQL> SQL> SQL> select extract(emps, "/emps/emp/home_address/text()" )

 2  from myTable
 3  /

EXTRACT(EMPS,"/EMPS/EMP/HOME_ADDRESS/TEXT()")

---

address 1 1 row selected. SQL> SQL> SQL> drop table myTable; Table dropped. SQL> SQL> SQL></source>

Without the text() operator, returns node name + text value

   <source lang="sql">

SQL> CREATE TABLE myTable(

 2      id  NUMBER PRIMARY KEY
 3      ,doc XMLType NOT NULL
 4  )
 5  XMLTYPE doc STORE AS CLOB
 6  /

Table created. SQL> SQL> SQL> select extract(doc, "/message/greeting")

 2  from myTable;

no rows selected SQL> SQL> SQL> drop table myTable; Table dropped.</source>

xmlagg and xmlforest

   <source lang="sql">

SQL> CREATE TABLE products(

 2    product_id              NUMBER(6),
 3    name            VARCHAR2(50),
 4    category        VARCHAR2(50),
 5    price      NUMBER(8,2),
 6    min_price       NUMBER(8,2)
 7  );

Table created. SQL> select xmlelement( "Prodcategory",

 2            xmlattributes(p.category as "Category"),
 3            xmlagg(xmlelement("Product",
 4            xmlforest(p.name as "Name"))))
 5  from products p
 6  group by p.category;

no rows selected SQL> SQL> drop table products; Table dropped.</source>