Introduction
In Part IV of my Sales Order Workshop, I had presented a basic example using the XML data type introduced by SQL Server 2005. Recently there were some questions and requests in the discussion forum asking for more detailed examples showing XML processing.
I also had another article published with some advanced XML examples and I am trying to present a few more examples in this article.
One of the most useful methods exposed by the XML data type is the Value() method. Here, I am presenting 9 more examples which demonstrates the different XML operations that we could perform with the Value() method.
Examples
1 /*
2 The following TSQL retrieves attribute values from the XML variable.
3 Attribute names are prefixed with "@".
4 */
5
6 DECLARE @x XML
7 SET @x = '
8
9
10
11
12
13
14
15
16
17
18
19 '
20
21 SELECT
22 x.item.value('@code[1]', 'VARCHAR(20)') AS ItemCode,
23 x.item.value('@category[1]', 'VARCHAR(20)') AS category,
24 x.item.value('@subcategory[1]', 'VARCHAR(20)') AS subcategory
25 FROM @x.nodes('//orderInfo/item') AS x(item)
26
27 /*
28 OUTPUT:
29
30 ItemCode category subcategory
31 -------------------- -------------------- --------------------
32 A001 FOOD Candies
33 A002 FOOD Biscuits
34
35 (2 row(s) affected)
36 */
1 /*
2 The following TSQL retrives values from XML nodes.
3 Note that, here we dont use the "@" sign to indicate that
4 we need values of nodes not attributes.
5 */
6
7 DECLARE @x XML
8 SET @x = '
9
10
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12
13
14
15
16
17
18
19
20 '
21
22 SELECT
23 x.item.value('description[1]', 'VARCHAR(20)') AS description,
24 x.item.value('qty[1]', 'INT') AS qty,
25 x.item.value('rate[1]', 'FLOAT') AS rate
26 FROM @x.nodes('//orderInfo/item') as x(item)
27
28 /*
29 OUTPUT:
30
31 description qty rate
32 -------------------- ----------- ----------------------
33 Nestle Munch 10 11.25
34 Britania Good Day 15 12.25
35
36 (2 row(s) affected)
37 */
1 /*
2 Well, this query retrieves attribute values as well as values
3 from nodes. Note that attribute values are specified with an "@"
4 character.
5 */
6 DECLARE @x XML
7 SET @x = '
8
9
10
11
12
13
14
15
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17
18
19 '
20
21 SELECT
22 x.item.value('@code[1]', 'VARCHAR(20)') AS ItemCode,
23 x.item.value('@category[1]', 'VARCHAR(20)') AS category,
24 x.item.value('@subcategory[1]', 'VARCHAR(20)') AS subcategory,
25 x.item.value('description[1]', 'VARCHAR(20)') AS description,
26 x.item.value('qty[1]', 'INT') AS qty,
27 x.item.value('rate[1]', 'FLOAT') AS rate
28 FROM @x.nodes('//orderInfo/item') AS x(item)
29
30 /*
31 OUTPUT:
32
33 ItemCode category subcategory description qty rate
34 -------------------- -------------------- -------------------- -------------------- ----------- ----------------------
35 A001 FOOD Candies Nestle Munch 10 11.25
36 A002 FOOD Biscuits Britania Good Day 15 12.25
37
38 (2 row(s) affected)
39 */
1 /*
2 The following example demonstrates how to extract the value
3 from a given row. This example extracts a value from the first
4 row.
5
6 The first example selects the value from the first row.
7 The second example adds an alias to the result column.
8 The third example assigns the result to a variable.
9 */
10
11 DECLARE @x XML
12 SET @x = '
13
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18
19
20
21
22
23
24 '
25
26 SELECT @x.value('(/orderInfo/item/@code)[1]', 'VARCHAR(20)')
27
28 SELECT @x.value('(/orderInfo/item/@code)[1]', 'VARCHAR(20)') AS Code
29
30 DECLARE @code VARCHAR(20)
31 SELECT @code = @x.value('(/orderInfo/item/@code)[1]', 'VARCHAR(20)')
32 SELECT @code as Code
33
34 /*
35 OUTPUT:
36
37 --------------------
38 A001
39
40 (1 row(s) affected)
41
42 Code
43 --------------------
44 A001
45
46 (1 row(s) affected)
47
48 Code
49 --------------------
50 A001
51
52 (1 row(s) affected)
53 */
54
1 /*
2 The following example retrieves the value from the second row.
3 */
4
5 DECLARE @x XML
6 SET @x = '
7
8
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12
13
14
15
16
17
18 '
19
20 SELECT @x.value('(/orderInfo/item/@code)[2]', 'VARCHAR(20)')
21
22 /*
23 OUTPUT:
24
25 --------------------
26 A002
27
28 (1 row(s) affected)
29 */
30
1 /*
2 The following example retrieves the value of an
3 element from the first row.
4 */
5 DECLARE @x XML
6 SET @x = '
7
8
9
10
11
12
13
14
15
16
17
18 '
19
20 SELECT @x.value('(/orderInfo/item/description)[1]', 'VARCHAR(20)')
21 /*
22 OUTPUT:
23
24 --------------------
25 Nestle Munch
26
27 (1 row(s) affected)
28 */
29
1 /*
2 The following example retrieves the value of an
3 element from the second row.
4 */
5 DECLARE @x XML
6 SET @x = '
7
8
9
10
11
12
13
14
15
16
17
18 '
19
20 SELECT @x.value('(/orderInfo/item/description)[2]', 'VARCHAR(20)')
21 /*
22 OUTPUT:
23
24 --------------------
25 Britania Good Day
26
27 (1 row(s) affected)
28 */
29
1 /*
2 Now let us have a look at filtering results. The following
3 example applies a filter on an attribute value.
4 */
5 DECLARE @x XML
6 SET @x = '
7
8
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12
13
14
15
16
17
18 '
19
20 SELECT
21 x.item.value('@code[1]', 'VARCHAR(20)') AS ItemCode,
22 x.item.value('@subcategory[1]', 'VARCHAR(20)') AS subcategory,
23 x.item.value('description[1]', 'VARCHAR(20)') AS description,
24 x.item.value('qty[1]', 'INT') AS qty
25 FROM @x.nodes('//orderInfo/item') AS x(item)
26 WHERE x.item.value('@code[1]', 'VARCHAR(20)') = 'A002'
27
28 /*
29 OUTPUT:
30
31 ItemCode subcategory description qty
32 -------------------- -------------------- -------------------- -----------
33 A002 Biscuits Britania Good Day 15
34
35 (1 row(s) affected)
36 */
1 /*
2 The following example applies a filter on the value
3 of an element.
4 */
5 DECLARE @x XML
6 SET @x = '
7
8
9
10
11
12
13
14
15
16
17
18 '
19
20 SELECT
21 x.item.value('@code[1]', 'VARCHAR(20)') AS ItemCode,
22 x.item.value('@subcategory[1]', 'VARCHAR(20)') AS subcategory,
23 x.item.value('description[1]', 'VARCHAR(20)') AS description,
24 x.item.value('qty[1]', 'INT') AS qty
25 FROM @x.nodes('//orderInfo/item') AS x(item)
26 WHERE x.item.value('description[1]', 'VARCHAR(20)') = 'Britania Good Day'
27
28 /*
29 OUTPUT:
30
31 ItemCode subcategory description qty
32 -------------------- -------------------- -------------------- -----------
33 A002 Biscuits Britania Good Day 15
34
35 (1 row(s) affected)
36 */
Conclusions
In this article, I have presented a few examples using the Value() method exposed by the XML data type. I will cover the other methods in a later article.