[Solved] XML nodes with SQL

Question

Please try the following solution. What we are doing here is called shredding, i.e. converting XML into rectangular/relational format.

I am shooting from the hip because DDL and sample data population were not provided.

The provided XML is not well-formed due to missing root element, but SQL Server allows to handle XML fragments.

We are using XQuery and its .nodes() and .value() methods.

SQL, Method #1

-- DDL and sample data population, start
DECLARE @xml XML =
N'<DW>
    <KS>
        <KeyInfo Name="IlluSetting">
            <KeyTypeValue>Text</KeyTypeValue>
            <ValueString>yDipol90</ValueString>
        </KeyInfo>
        <KeyInfo Name="IlluSetting2">
            <KeyTypeValue>Text</KeyTypeValue>
            <ValueString>yDipol</ValueString>
        </KeyInfo>
    </KS>
    <MDESC>Tx [mrad]</MDESC>
    <MNUMBER>0.12102</MNUMBER>
</DW>
<DW>
    <KS>
        <KeyInfo Name="IlluSetting3">
            <KeyTypeValue>Text</KeyTypeValue>
            <ValueString>yDipol80</ValueString>
        </KeyInfo>
    </KS>
    <MDESC>Ty [mrad]</MDESC>
    <MNUMBER>0.12102</MNUMBER>
</DW>';
-- DDL and sample data population, end

SELECT c.value('KeyInfo[1]/@Name', 'VARCHAR(30)') AS name1
    , c.value('(KeyInfo[1]/ValueString/text())[1]', 'VARCHAR(30)') AS ValueString1
    , COALESCE(c.value('KeyInfo[2]/@Name', 'VARCHAR(30)'), '') AS name2
    , COALESCE(c.value('(KeyInfo[2]/ValueString/text())[1]', 'VARCHAR(30)'), '') AS ValueString2
FROM @xml.nodes('/DW/KS') AS t(c);

Output

+--------------+--------------+--------------+--------------+
|    name1     | ValueString1 |    name2     | ValueString2 |
+--------------+--------------+--------------+--------------+
| IlluSetting  | yDipol90     | IlluSetting2 | yDipol       |
| IlluSetting3 | yDipol80     |              |              |
+--------------+--------------+--------------+--------------+

SQL, Method #2

DECLARE @CrLf CHAR(2) = CHAR(13) + CHAR(10)
   , @tokenCounter INT
   , @i INT = 1;

-- Calculate max number of tokens in the <KS>
SET @tokenCounter = (SELECT MAX(c.value('count(KeyInfo)', 'INT'))
FROM @xml.nodes('/DW/KS') AS t(c));

DECLARE @SQL NVARCHAR(MAX) = 'SELECT ';

WHILE @i <= @tokenCounter BEGIN
    SET @SQL += IIF(@i>1,', ','') + 'COALESCE(c.value(''KeyInfo[' + CAST(@i AS VARCHAR(3)) + ']/@Name'', ''VARCHAR(30)''), '''') AS NAME' + CAST(@i AS VARCHAR(3)) + @CrLf
    SET @SQL += ', COALESCE(c.value(''(KeyInfo[' + CAST(@i AS VARCHAR(3)) + ']/ValueString/text())[1]'', ''VARCHAR(30)''), '''') AS ValueString' + CAST(@i AS VARCHAR(3)) + @CrLf

    SET @i += 1
END

SET @SQL += 'FROM @xml.nodes(''/DW/KS'') AS t(c);';

-- just to see it
PRINT @sql;

-- we are ready at this point
EXEC sp_executesql @stmt = @SQL, @params = N'@xml xml', @xml = @xml;

Accepted Answer