How to get distinct values in XQuery from XML database ?

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XML

script

In below xml:

<mo>
	<customers>
	<customer cno="2222">
			<cname>Charles</cname>
			<street>123 Main St.</street>
			<city>Wichita</city>
			<zip>67226</zip>
			<phone>316-636-5555</phone>
		</customer>
		<customer cno="1000">
			<cname>Bismita</cname>
			<street>Ashford Dunwoody</street>
			<city>Wichita</city>
			<zip>67226-1555</zip>
			<phone>000-000-0000</phone>
		</customer>		
	</customers>
	
	<employees>
	<employee eno="1000">
			<ename>Jones</ename>
			<city>Wichita</city>
			<zip>67226-1555</zip>
			<hdate>1995-12-12</hdate>
		</employee>
		<employee eno="2000">
			<ename>Asmit</ename>
			<city>Wichita</city>
			<zip>67226-1555</zip>
			<hdate>1967-08-13</hdate>
		</employee>
		<employee eno="1003">
			<ename>Axaya</ename>
			<city>BBSR</city>
			<zip>67226</zip>
			<hdate>1978-08-13</hdate>
		</employee>		
	</employees>
	
	
	<parts>
		<part pno="10506">			
			<pname>Land Before Time I</pname>
			<qoh>200</qoh>
			<price>319.99</price>
			<level>20</level>
		</part>
		<part pno="10000">			
			<pname>Bottle</pname>
			<qoh>2</qoh>
			<price>3.00</price>
			<level>2</level>
		</part>
		<part pno="10508">			
			<pname>Land Before Time 3</pname>
			<qoh>202</qoh>
			<price>2.00</price>
			<level>22</level>
		</part>
		<part pno="10509">			
			<pname>Cycle</pname>
			<qoh>202</qoh>
			<price>1.00</price>
			<level>22</level>
		</part>
	</parts>
	
	<orders>	
		<order ono="1000" takenBy="1000" customer="2222" >
			<receivedDate>1967-08-17</receivedDate>
			<shippedDate>1967-08-13</shippedDate>
			<items>
				<item>
					<partNumber>10508</partNumber>
					<quantity>2</quantity>
				</item>
			</items>
		</order>
		<order ono="1001" takenBy="1000" customer="1000" >
			<receivedDate>1968-08-14</receivedDate>
			<shippedDate>1968-08-11</shippedDate>
			<items>
				<item>
					<partNumber>10000</partNumber>
					<quantity>2</quantity>
				</item>
				
			</items>
		</order>
		
		<order ono="1022" takenBy="1003"  customer="2222" >
			<receivedDate>1995-02-14</receivedDate>
			<shippedDate>1995-02-13</shippedDate>
			<items>
				<item>
					<partNumber>10000</partNumber>
					<quantity>1</quantity>
				</item>
				<item>
					<partNumber>10508</partNumber>
					<quantity>2</quantity>
				</item>
				<item>
					<partNumber>10509</partNumber>
					<quantity>3</quantity>
				</item>
			</items>
		</order>
		
	</orders>
</mo>

Two xquries are required.
1. Get the names of customers who have ordered parts from employees living in Wichita.
I have tried below xquery:

for
$c in /mo/customers/customer,
$e in /mo/employees/employee,
$p in /mo/parts/part,
$o in /mo/orders/order
where data($p/@pno)=$o/items/item/partNumber
and data($e/@eno)= data($o/@takenBy)
and $e/city='Wichita'
return $c/cname

Problem: Query returns duplicate values, how can I get distinct values ?

2. Get the names of customers who have ordered parts only from employees living in Wichita.
I have tried below xquery:

for
$c in /mo/customers/customer,
$e in /mo/employees/employee,
$p in /mo/parts/part,
$o in /mo/orders/order
where data($p/@pno)=$o/items/item/partNumber
and data($e/@eno)= data($o/@takenBy)
and data($e/city) eq("Wichita")
return $c/cname

Problem: Same result as query 1 with duplicate values.

Note: what should be the difference between two query by observing "living in Wichita and living only in wichita".

How can I get rid of returning duplicate values in these queries ?
Any help ?