Converting XML data to SQL table

Sorry, in my first attempt I completely misread your question and thought you'd like to get the data out of your XML. This is the approach to create such an XML out of table's data:

DECLARE @cust TABLE(ID INT, CustomerName VARCHAR(100),DateOfBirth DATE);
INSERT INTO @cust VALUES(1,'Jonny','1990-01-02T00:00:00')
                       ,(2,'Jimmy','1980-01-02T00:00:00');

DECLARE @ord TABLE(ID INT,CustomerID INT,OrderDate DATE, OrderAmount INT);
INSERT INTO @ord VALUES(1,1,'1993-02-03T00:00:00',1000)
                      ,(2,1,'1994-02-03T00:00:00',500)
                      ,(3,2,'1994-02-03T00:00:00',200);

SELECT c.CustomerName AS [@Name]
      ,c.DateOfBirth AS [@DateofBirth]
      ,(
        SELECT o.OrderDate
              ,o.OrderAmount
        FROM @ord AS o
        WHERE o.CustomerID=c.ID
        FOR XML PATH('OrderInfo'),TYPE
       )
FROM @cust AS c
FOR XML PATH('Customer'),ROOT('SalesDetails')

And this is the created XML

<SalesDetails>
  <Customer Name="Jonny" DateofBirth="1990-01-02">
    <OrderInfo>
      <OrderDate>1993-02-03</OrderDate>
      <OrderAmount>1000</OrderAmount>
    </OrderInfo>
    <OrderInfo>
      <OrderDate>1994-02-03</OrderDate>
      <OrderAmount>500</OrderAmount>
    </OrderInfo>
  </Customer>
  <Customer Name="Jimmy" DateofBirth="1980-01-02">
    <OrderInfo>
      <OrderDate>1994-02-03</OrderDate>
      <OrderAmount>200</OrderAmount>
    </OrderInfo>
  </Customer>
</SalesDetails>

Just for the case you want to read your XML, I let this appended

You can retrieve all the information like this:

The generated Index columns are IDs you can use to insert this into relational tables. The problem with your XML is, that the information about your target tabels is missing. But the rest should be easy for you.

Btw: I declared some more similar nodes to make the relational structure visible

DECLARE @x XML=
'<SalesDetails>
  <Customer Name="Johny" DateofBirth="1990-01-02T00:00:00">
    <OrderInfo>
      <OrderDate>1993-02-03T00:00:00</OrderDate>
      <OrderAmount>1000</OrderAmount>
    </OrderInfo>
    <OrderInfo>
      <OrderDate>1994-02-03T00:00:00</OrderDate>
      <OrderAmount>500</OrderAmount>
    </OrderInfo>
  </Customer>
  <Customer Name="Jimmy" DateofBirth="1980-01-02T00:00:00">
    <OrderInfo>
      <OrderDate>1994-02-03T00:00:00</OrderDate>
      <OrderAmount>200</OrderAmount>
    </OrderInfo>
    <OrderInfo>
      <OrderDate>1993-02-03T00:00:00</OrderDate>
      <OrderAmount>100</OrderAmount>
    </OrderInfo>
  </Customer>
</SalesDetails>';

WITH CustomerNodes AS
(
     SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS CustomerIndex
           ,Customer.value('@Name','varchar(max)') AS CustomerName
           ,Customer.value('@DateofBirth','date') AS CustomerDateOfBirth
           ,One.Customer.query('.') AS CustomerNode
     FROM @x.nodes('SalesDetails/Customer') AS One(Customer)
)
SELECT cn.*
      ,ROW_NUMBER() OVER(PARTITION BY cn.CustomerIndex ORDER BY (SELECT NULL)) AS OrderIndex
      ,OrderInfo.value('OrderDate[1]','date') AS OrderDate
      ,OrderInfo.value('OrderAmount[1]','int') AS OrderAmount
 FROM CustomerNodes AS cn
 CROSS APPLY cn.CustomerNode.nodes('Customer/OrderInfo') As The(OrderInfo)

The result:

Customer                 Order
ID   Name    DateOfBirth ID  OrderDate   OrderAmount
1   Johny   1990-01-02  1   1993-02-03  1000
1   Johny   1990-01-02  2   1994-02-03  500
2   Jimmy   1980-01-02  1   1994-02-03  200
2   Jimmy   1980-01-02  2   1993-02-03  100