Reading xml node elements in SQL Server

Consider the given data is available in Configuration table with column names KeyName and Value, as shown below:

Now if you want to read the data for Period and LastDate node available in Value column, use the query mentioned below:
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SELECT Value.value (' (/config/lastDate)[1]','Datetime') LastDate,
Value.value (' (/config/period)[1]','int')Period
FROM Configuration

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The output will be:

If you want to update any element value in the XML nodes then use the following query:

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SET @LastDate=?

UPDATE Configuration

SET Value.modify('

  replace value of (/config/lastDate/text())[1]

  with sql:variable("@LastDate") ')

where KeyName='Key_name'

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The same query can be written without using variable as well.