DB2 XQuery学习笔记
DB2 9有一个新特性就是增加XML类型数据存储，操作这种数据最理想的方式就是通过XQuery来进行，XQuery是XML数据检索的标准，可以在W3C网站上查看其规范。但是，XQuery需要数据的支持才能操作XML数据。说来麻烦，看看就明白了。
操作环境：
DB2 V9.1命令行
为了实践，首先从命令行连接到DB2数据库
db2 connect to dbname user username using password
然后设置语句的终止符为“~”
db2 -td~
下面就开始照着代码操作了。
db2 -td~

CREATE DATABASE xmltut USING CODESET GBK TERRITORY US~

CREATE TABLE Customer (Cid BIGINT NOT NULL PRIMARY KEY, Info XML)~

CREATE UNIQUE INDEX cust_cid_xmlidx ON Customer(Info)
GENERATE KEY USING XMLPATTERN
'declare default element namespace "http://posample.org"~ /customerinfo/@Cid'
AS SQL DOUBLE~

INSERT INTO Customer (Cid, Info) VALUES (1000,
'<customerinfo xmlns="http://posample.org" Cid="1000">
<name>Kathy Smith</name>
<addr country="Canada">
<street>5 Rosewood</street>
<city>Toronto</city>
<prov-state>Ontario</prov-state>
<pcode-zip>M6W 1E6</pcode-zip>
</addr>
<phone type="work">416-555-1358</phone>
</customerinfo>')~

INSERT INTO Customer (Cid, Info) VALUES (1002,
'<customerinfo xmlns="http://posample.org" Cid="1002">
<name>Jim Noodle</name>
<addr country="Canada">
<street>25 EastCreek</street>
<city>Markham</city>
<prov-state>Ontario</prov-state>
<pcode-zip>N9C 3T6</pcode-zip>
</addr>
<phone type="work">905-555-7258</phone>
</customerinfo>')~

INSERT INTO Customer (Cid, Info) VALUES (1003,
'<customerinfo xmlns="http://posample.org" Cid="1003">
<name>Robert Shoemaker</name>
<addr country="Canada">
<street>1596 Baseline</street>
<city>Aurora</city>
<prov-state>Ontario</prov-state>
<pcode-zip>N8X 7F8</pcode-zip>
</addr>
<phone type="work">905-555-2937</phone>
</customerinfo>')~

SELECT * from Customer~

UPDATE customer SET info =
'<customerinfo xmlns="http://posample.org" Cid="1002">
<name>Jim Noodle</name>
<addr country="Canada">
<street>1150 Maple Drive</street>
<city>Newtown</city>
<prov-state>Ontario</prov-state>
<pcode-zip>Z9Z 2P2</pcode-zip>
</addr>
<phone type="work">905-555-7258</phone>
</customerinfo>'
WHERE XMLEXISTS (
'declare default element namespace "http://posample.org";
$doc/customerinfo[@Cid = 1002]'
passing INFO as "doc")~

DELETE FROM Customer
WHERE XMLEXISTS (
'declare default element namespace "http://posample.org";
$doc/customerinfo[@Cid = 1003]'
passing INFO as "doc")~

SELECT count(*) from Customer~

SELECT XMLQUERY (
'declare default element namespace "http://posample.org";
for $d in $doc/customerinfo
return <out>{$d/name}</out>'
passing INFO as "doc")
FROM Customer as c
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$i/customerinfo/addr[city="Toronto"]' passing c.INFO as "i")~

UPDATE COMMAND OPTIONS USING i ON~

-- 不使用SQL的情况下检索INFO列中所有的XML文档
XQUERY db2-fn:xmlcolumn ('CUSTOMER.INFO')~
-- 相当于
SELECT Info FROM Customer~

-- 全查询
XQUERY db2-fn:sqlquery ('SELECT Info FROM Customer')~

-- 检索和过滤XML值
XQUERY declare default element namespace "http://posample.org";
for $d in db2-fn:xmlcolumn('CUSTOMER.INFO')/customerinfo
where $d/addr/city="Toronto"
return <out>{$d/name}</out>~

XQUERY declare default element namespace "http://posample.org";
for $d in db2-fn:sqlquery(
'SELECT INFO
FROM CUSTOMER
WHERE Cid < 2000')/customerinfo
where $d/addr/city="Toronto"
return <out>{$d/name}</out>~

-- XML模式注册
REGISTER XMLSCHEMA 'http://posample.org'
FROM 'file:///<C:/>customer.xsd' AS posample.customer COMPLETE~

REGISTER XMLSCHEMA [url]http://posample.org/product.xsd[/url] FROM product.xsd \
AS myschema.product
COMPLETE XMLSCHEMA myschema.product~

REGISTER XMLSCHEMA [url]http://posample.org/product.xsd[/url] FROM product.xsd \
AS myschema.product COMPLETE~

customer.xsd
<?xml version="1.0"?>
<xs:schema targetNamespace="http://podemo.org" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
  <xs:element name="customerinfo">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="name" type="xs:string" minOccurs="1" />
        <xs:element name="addr" minOccurs="1" maxOccurs="unbounded">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="street" type="xs:string" minOccurs="1" />
              <xs:element name="city" type="xs:string" minOccurs="1" />
              <xs:element name="prov-state" type="xs:string" minOccurs="1" />
              <xs:element name="pcode-zip" type="xs:string" minOccurs="1" />
            </xs:sequence>
            <xs:attribute name="country" type="xs:string" />
          </xs:complexType>
        </xs:element>
        <xs:element name="phone" nillable="true" minOccurs="0" maxOccurs="unbounded">
          <xs:complexType>
            <xs:simpleContent>
              <xs:extension base="xs:string">
                <xs:attribute name="type" form="unqualified" type="xs:string" />
              </xs:extension>
            </xs:simpleContent>
          </xs:complexType>
        </xs:element>
        <xs:element name="assistant" minOccurs="0" maxOccurs="unbounded">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="name" type="xs:string" minOccurs="0" />
              <xs:element name="phone" nillable="true" minOccurs="0" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:simpleContent  >
                    <xs:extension base="xs:string">
                      <xs:attribute name="type" type="xs:string" />
                    </xs:extension>
                  </xs:simpleContent>
                </xs:complexType>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
      <xs:attribute name="Cid" type="xs:string" />
    </xs:complexType>
  </xs:element>
</xs:schema>

INSERT INTO Customer(Cid, Info) VALUES (1003, XMLVALIDATE (XMLPARSE (DOCUMENT
'<customerinfo xmlns="http://posample.org" Cid="1003">
<name>Robert Shoemaker</name>
<addr country="Canada">
<street>1596 Baseline</street>
<city>Aurora</city>
<prov-state>Ontario</prov-state>
<pcode-zip>N8X 7F8</pcode-zip>
</addr>
<phone type="work">905-555-7258</phone>
<phone type="home">416-555-2937</phone>
<phone type="cell">905-555-8743</phone>
<phone type="cottage">613-555-3278</phone>
</customerinfo>' PRESERVE WHITESPACE )
ACCORDING TO XMLSCHEMA ID posample.customer ))~

CREATE TABLE Customer (Cid BIGINT NOT NULL PRIMARY KEY,
Info XML,
History XML)

CREATE TABLE MyCustomer LIKE Customer;
ALTER TABLE MyCustomer ADD COLUMN Preferences XML;

JDBC插入XML
PreparedStatement insertStmt = null;
String sqls = null;
int cid = 1015;
sqls = "INSERT INTO MyCustomer (Cid, Info) VALUES (?, ?)";
insertStmt = conn.prepareStatement(sqls);
insertStmt.setInt(1, cid);
File file = new File("c6.xml");
insertStmt.setBinaryStream(2, new FileInputStream(file), (int)file.length());
insertStmt.executeUpdate();

JDBC更新XML
PreparedStatement updateStmt = null;
String sqls = null;
int cid = 1004;
sqls = "UPDATE MyCustomer SET Info=? WHERE Cid=?";
updateStmt = conn.prepareStatement(sqls);
updateStmt.setInt(1, cid);
File file = new File("c7.xml");
updateStmt.setBinaryStream(2, new FileInputStream(file), (int)file.length());
updateStmt.executeUpdate();

-- 删除数据
DELETE FROM MyCustomer
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$d//addr[city="Markham"]' passing INFO as "d")~

-- XML列创建触发器  
CREATE TRIGGER UPDAFTR
AFTER UPDATE OF Info
ON MyCustomer
REFERENCING NEW AS N
FOR EACH ROW
BEGIN ATOMIC
INSERT INTO CustLog VALUES(N.CID, CURRENT TIMESTAMP, 'Update');
END~

CREATE TRIGGER INSAFTR
AFTER INSERT ON Customer
REFERENCING NEW AS N
FOR EACH ROW
BEGIN ATOMIC
INSERT INTO CustLog VALUES(N.CID, CURRENT TIMESTAMP, 'Insert');
END~

-- XML解析
INSERT INTO MyCustomer (Cid, Info)
VALUES (?, xmlparse(document cast(? as clob(1k)) preserve whitespace))~

-- 在XQuery中，查询可以调用下列函数之一来获取DB2数据库中的输入XML数据：db2-fn:sqlquery 和 db2-fn:xmlcolumn。db2-fn:xmlcolumn函数将检索整个XML列，而db2-fn:sqlquery将检索基于SQL查询的XML值。

db2-fn:xmlcolumn('BUSINESS.ORDERS.PURCHASE_ORDER')/shipping_address/city

db2-fn:sqlquery("
SELECT purchase_order FROM business.orders
WHERE ship_date = '2005-06-15' ")/shipping_address/city

SQL是一种不区分大小写的语言
XQuery是一种区分大小写的语言

函数
XMLQUERY
XMLTABLE
谓词
XMLEXISTS

SELECT XMLQUERY ('declare default element namespace "http://posample.org";
$d/customerinfo/phone' passing INFO as "d")
FROM CUSTOMER~

VALUES (XMLQUERY ('declare default element namespace "http://posample.org";
db2-fn:xmlcolumn("CUSTOMER.INFO")/customerinfo/phone'))~

SELECT Cid, XMLQUERY ('declare default element namespace "http://posample.org";
$d//addr[city="Aurora"]' passing INFO as "d") AS ADDRESS
FROM CUSTOMER~

SELECT Cid, XMLQUERY ('declare default element namespace "http://posample.org";
$d/customerinfo/addr' passing c.INFO as "d")
FROM Customer as c
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$d//addr[city="Aurora"]' passing c.INFO as "d")~

SELECT R.Pid
FROM PURCHASEORDER P, PRODUCT R
WHERE R.NAME =
XMLCAST( XMLQUERY ('declare default element namespace "http://posample.org";
$d/PurchaseOrder/itemlist/item/product/name'
PASSING P.PORDER AS "d") AS VARCHAR(128))~

SELECT Pid
FROM PRODUCT
ORDER BY XMLCAST(XMLQUERY ('declare default element namespace "http://posample.org";
$d/product/description/name'
PASSING DESCRIPTION AS "d") AS VARCHAR(128))~

SELECT X.*
FROM XMLTABLE (xmlnamespaces (DEFAULT "http://posample.org"),
'db2-fn:xmlcolumn("CUSTOMER.INFO")/customerinfo'
COLUMNS "CUSTNAME" CHAR(30) PATH 'name',
"PHONENUM" XML PATH 'phone')
as X~

SELECT X.*
FROM XMLTABLE (xmlnamespaces (DEFAULT "http://posample.org"),
'db2-fn:xmlcolumn("CUSTOMER.INFO")/customerinfo'
COLUMNS "CUSTNAME" CHAR(30) PATH 'name',
"PHONENUM" XML PATH 'phone')
as X
ORDER BY X.CUSTNAME~

INSERT INTO CUSTPHONE
SELECT X.*
FROM XMLTABLE (XMLNAMESPACES (DEFAULT 'http://posample.org'),
'db2-fn:xmlcolumn("CUSTOMER.INFO")/customerinfo'
COLUMNS
"CUSTNAME" CHAR(30) PATH 'name',
"PHONENUM" XML PATH 'document{<allphones>{phone}</allphones>}'
)as X~

SELECT X.*
FROM CUSTOMER C, XMLTABLE (xmlnamespaces (DEFAULT 'http://posample.org'),
'$cust/customerinfo/phone' PASSING C.INFO as "cust"
COLUMNS "CUSTNAME" CHAR(30) PATH '../name',
"PHONETYPE" CHAR(30) PATH '@type',
"PHONENUM" CHAR(15) PATH '.'
)as X~

SELECT X.* FROM CUSTOMER C, XMLTABLE (xmlnamespaces (DEFAULT 'http://posample.org'),
'$cust/customerinfo/phone' PASSING C.INFO as "cust"
COLUMNS "CUSTNAME" CHAR(30) PATH '../name',
"PHONETYPE" CHAR(30) PATH '@type',
"PHONENUM" XML PATH '.' ) as X~

SELECT Cid
FROM CUSTOMER
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$d//addr[city="Toronto"]' passing INFO as "d")~

SELECT *
FROM CUSTOMER
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$d/customerinfo[@Cid=1000]' passing INFO as "d")~

SELECT *
FROM CUSTOMER
WHERE XMLEXISTS ('declare default element namespace "http://posample.org";
$d/customerinfo/@Cid=1000' passing INFO as "d")~

CREATE TABLE mytable (id BIGINT, xmlcol XML)~

CREATE INDEX myidx ON mytable(xmlcol)
GENERATE KEY USING XMLPATTERN '//text()' AS SQL VARCHAR(255)~

SELECT xmlcol FROM mytable
WHERE XMLEXISTS('$doc/CUSTOMER/ORDERS/ORDERKEY/text()="A512" '
PASSING xmlcol AS "doc")~

SELECT xmlcol FROM mytable
WHERE XMLEXISTS('$doc/CUSTOMER[ORDERS/ORDERKEY/text()="A512"] '
PASSING xmlcol AS "doc")~

-- XML数据类型转换
SELECT XMLQUERY ('declare default element namespace "http://posample.org";
$d/customerinfo/addr' passing c.INFO as "d")
FROM Customer as c
WHERE XMLEXISTS('declare default element namespace "http://posample.org";
$d//addr[city=$cityName]'
passing c.INFO as "d",
'Aurora' AS "cityName")~

SELECT XMLQUERY ('declare default element namespace "http://posample.org";
$d/customerinfo/addr' passing c.INFO as "d")
FROM Customer as c
WHERE XMLEXISTS('declare default element namespace "http://posample.org";
$d//addr[city=$cityName]'
passing c.INFO as "d",
CAST (? AS VARCHAR(128)) AS "cityName")~

SELECT companydocs FROM companyinfo
WHERE XMLEXISTS('$x/company/emp[@salary > 35000]'
PASSING companydocs AS "x")~

CREATE INDEX empindex on companyinfo(companydocs)
GENERATE KEY USING XMLPATTERN '//@salary' AS SQL DOUBLE~

CREATE INDEX empindex on companyinfo(companydocs)
GENERATE KEY USING XMLPATTERN '/company/emp/@salary'
AS SQL DOUBLE~

SELECT companydocs FROM companyinfo
WHERE XMLEXISTS('$x/company/emp[@id="31664"]'
PASSING companydocs AS "x")~

SELECT companydocs FROM companyinfo
WHERE XMLEXISTS('$x/company/emp/dept[@id="K55"]
PASSING companydocs AS "x")~

时间很紧，学习周期为90分钟，大部分代码没有注释，运行下看看，再参考DB2官方文档看明白应该不成问题 。
SELECT X.* FROM WSYW_QYDJ AS A,
    XMLTABLE('$nr/MainBody/DJ_ZT' passing A.XMLNR as "nr" columns
  "BS" VARCHAR(24) PATH 'BS',
  "MC" VARCHAR(240) PATH 'MC',
  "ZH" VARCHAR(100) PATH 'ZH',
  "XZQH_DM" VARCHAR(24) PATH 'XZQH_DM',
  "FDDBR" VARCHAR(100) PATH 'FDDBR',
  "JYDZ" VARCHAR(240) PATH 'JYDZ',
  "QYLX_ZL" VARCHAR(4) PATH 'QYLX_ZL',
  "QYLX_XL" VARCHAR(4) PATH 'QYLX_XL',
  "CJRQ" VARCHAR(64) PATH 'CJRQ') AS X
WHERE A.UHID = ? AND A.ZT = ?

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