----------------------------------
SELECT - Single Table - Direct SQL
----------------------------------
SELECT CustomerID, CompanyName, Country, City
FROM Customers
WHERE (Country = 'Germany' AND City = 'Berlin')
OR (Country = 'UK' AND City = 'London')


-------------------------------
SELECT - Single Table - XML SQL
-------------------------------
<root>
    <statement>
        <dbTableName action="SELECT">
            <table>Customers</table>
            <access>
                <CustomerID/>
                <CompanyName/>
                <City/>
                <Country/>
            </access>
            <key>
                <Country>Germany</Country>
                <City>Berlin</City>
            </key>
            <key>
                <Country>UK</Country>
                <City>London</City>
            </key>
        </dbTableName>
    </statement>
</root>

Notes:
1) <root> can be any name, better consistently stick to <root>.
2) <statement> can be any name, can use generic <statement> or others unique name based on need.
3) <dbTableName> can be any name, better stick to default <dbTableName> for consistent reason.
4) <key> can be multiple different names like (key1, key2, keyXYZ) but need starts with "key".
5) all columns under same <key> is using AND operator.
6) Between different <key> is using OR operator.

--------------------------------
SELECT - Table Join - Direct SQL
--------------------------------
SELECT C.CustomerID, C.CompanyName, C.Country, C.City, O.OrderID
FROM Customers C, Orders O
WHERE C.Country = 'Germany' AND C.City = 'Berlin'
AND C.CustomerID = O.CustomerID


-----------------------------------------------
SELECT - Table Join - SQL_QUERY with Parameters
-----------------------------------------------
<root>
    <statement>
        <dbTableName action="SQL_QUERY">
            <access>SELECT C.CustomerID, C.CompanyName, C.Country, C.City, O.OrderID
FROM Customers C, Orders O
WHERE C.Country = '$Country$' AND C.City = '$City$'
AND C.CustomerID = O.CustomerID</access>
            <key>
                <Country>Germany</Country>
                <City>Berlin</City>
            </key>
        </dbTableName>
    </statement>
</root>



--------------------------
SELECT - View - Direct SQL
--------------------------
SELECT * FROM "Order Subtotals"


--------------------------
SELECT - View - Direct SQL
--------------------------
<root>
    <statement>
        <dbTableName action="SELECT">
            <table>"Order Subtotals"</table>
            <access>
                <OrderID/>
                <Subtotal/>
            </access>
        </dbTableName>
    </statement>
</root>


------------------------------------------------------------
SELECT - View - Direct SQL with filtering (compareOperation)
------------------------------------------------------------
SELECT * FROM "Order Subtotals"
WHERE Subtotal >= 10000


---------------------------------------------------------
SELECT - View - XML SQL with filtering (compareOperation)
---------------------------------------------------------
<root>
    <statement>
        <dbTableName action="SELECT">
            <table>"Order Subtotals"</table>
            <access>
                <OrderID/>
                <Subtotal/>
            </access>
			<key>
				<Subtotal compareOperation="GTEQ">10000</Subtotal>
			</key>
        </dbTableName>
    </statement>
</root>


-----------------------------------------
SELECT - View - SQL_QUERY with Parameters
-----------------------------------------
<root>
    <statement>
        <dbTableName action="SQL_QUERY">
            <access>SELECT TOP 3 * FROM "Order Subtotals"
WHERE Subtotal >= $Subtotal$
ORDER BY Subtotal DESC</access>
            <key>
                <Subtotal>10000</Subtotal>
            </key>
        </dbTableName>
    </statement>
</root>


Reference:
https://help.sap.com/docs/integration-suite/sap-integration-suite/jdbc-receiver-adapter

Defining XML Documents for Message Protocol XML SQL Format:
https://help.sap.com/viewer/5cf7d2de571a45cc81f91261668b7361/7.5.4/en-US/2e96fd3f2d14e869e10000000a155106.html

Defining a SELECT Statement
https://help.sap.com/docs/SAP_NETWEAVER_750/5cf7d2de571a45cc81f91261668b7361/447b7171fde93673e10000000a114a6b.html?version=7.5.4