使用T-SQL和XQUERY解析XML - 搜索特定值

时间:2013-06-27 20:11:40

标签: sql-server sql-server-2008 tsql xpath xquery

我有一些应用程序的属性以XML格式传递给我。我需要按名称解析属性,并将值分配给我的数据库中的相应列。

我目前正在SSIS脚本组件中解析它,但它需要很长时间才能完成。我希望使用XQUERY有一个简单的解决方案,但我找不到我要找的东西。

以下是我收到的xml示例:

<properties>
    <property>
        <name>DISMISS_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>SHOW_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>DEFAULT_SETTING</name>
        <value>DEFAULT</value>
    </property>
</properties>

所以,如果我查看第一个属性元素,我会将值DEFAULT分配给我的数据库中的DISMISS_SETTING列。此外,重要的是要注意,值的顺序和组合可能没有特定的顺序。

4 个答案:

答案 0 :(得分:9)

使用value() Method (xml Data Type)从XML中提取值。在XQuery表达式中检查谓词中所需的名称。

select 
  @XML.value('(/properties/property[name = "DISMISS_SETTING"]/value/text())[1]', 'nvarchar(100)') as DISMISS_SETTING,
  @XML.value('(/properties/property[name = "SHOW_SETTING"]/value/text())[1]', 'nvarchar(100)') as SHOW_SETTING,
  @XML.value('(/properties/property[name = "DEFAULT_SETTING"]/value/text())[1]', 'nvarchar(100)') as DEFAULT_SETTING

SQL Fiddle

答案 1 :(得分:1)

如果您正在寻找TSQL解决方案,并且我的结果表看起来如下所示:

| DISMISS_SETTING | SHOW_SETTING | DEFAULT_SETTING |
|-----------------|--------------|-----------------|
| DEFAULT         | DEFAULT      | DEFAULT         |

你应该使用我稍后将描述的一组脚本。最初,您需要创建动态查询的动态存储过程 - 它使您可以在这些列下将数据插入到表中,这些列在运行时(XML解析的时间)之前是未知的:

create procedure mysp_update (@table_name nvarchar(50), @column_name nvarchar(50), @column_value nvarchar(50))
as
begin
    declare @rows_count int
    declare @query nvarchar(500)
    declare @parm_definition nvarchar(100)

    -- Get rows count in your table using sp_executesql and an output parameter        
    set @query = N'select @rows_count = count(1) from ' +  quotename(@table_name)
    exec sp_executesql @query, N'@rows_count INT OUTPUT', @rows_count OUTPUT

    -- If no rows - insert the first one, else - update existing
    if @rows_count = 0
        set @query = N'insert into ' + quotename(@table_name) + N'(' + quotename(@column_name) + N') values (@column_value)'        
    else
        set @query = N'update ' + quotename(@table_name) + N'set ' + quotename(@column_name) + N' = @column_value' 

    set @parm_definition = N'@column_value nvarchar(50)'
    exec sp_executesql @query, @parm_definition, @column_value = @column_value
end
go

接下来,使用此XQuery / SQL语句从您正在寻找的信息中提取(来自XML):

-- Define XML object based on which insert statement will be later created   
declare @data xml = N'<properties>
    <property>
        <name>DISMISS_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>SHOW_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>DEFAULT_SETTING</name>
        <value>DEFAULT</value>
    </property>
</properties>'

-- Declare temporary container
declare @T table(id int identity, name nvarchar(50), value nvarchar(50))

-- Push the extracted nodes values into it
insert into @T(name, value)
select
    x.value(N'(name)[1]', N'nvarchar(50)'),
    x.value(N'(value)[1]', N'nvarchar(50)')
from
    @data.nodes(N'/properties/property') AS XTbl(x)

之后,提取的数据对 [name,value] 存储在表变量@T中。最后,迭代这些临时元数据并在主表的相应列名中插入

declare @name nvarchar(50), @value nvarchar(50), @current_id int = 1

-- Fetch first row
select @name = name, @value = value 
from @T where id = @current_id

while @@rowcount = 1
begin
    -- Execute SP here (btw: SP cannot be executed from select statement)
    exec mysp_update N'TableName', @name, @value

    -- Fetch next row
    set @current_id = @current_id + 1

    select @name = name, @value = value 
    from @T where id = @current_id  
end 

提供的解决方案允许您在XML中拥有可变数量的节点,无需任何特定顺序。

请注意,负责从XML提取数据和插入主表的逻辑可以包含在附加的存储过程中,例如: mysp_xml_update (@data xml)然后以干净的方式执行:exec mysp_xml_update N'<properties>....</properties>

尽管如此,请使用SQL Fiddle自行尝试代码。

<强>更新

根据评论中的要求 - 应该执行一个大的更新,而不是按列顺序更新。为此,mysp_update应该被修改,例如以下方式:

create type HashTable as table(name nvarchar(50), value nvarchar(50))
go

create procedure mysp_update (@table_name nvarchar(50), @set HashTable readonly)
as
begin  
    -- Concatenate names and values (to be passed to insert statement below)
    declare @columns varchar(max)
    select @columns = COALESCE(@columns + ', ', '') + quotename(name) from @set
    declare @values varchar(max)
    select @values = COALESCE(@values + ', ', '') + quotename(value, '''') from @set

    -- Remove previous values
    declare @query nvarchar(500)
    set @query = N'delete from ' + quotename(@table_name)
    -- Insert new values to the table
    exec sp_executesql @query
    set @query = N'insert into ' + quotename(@table_name) + N'(' + @columns + N') values (' + @values + N')'    
    exec sp_executesql @query
end
go 

答案 2 :(得分:1)

您可以通过从xml中提取名称和值并围绕名称进行旋转来完成此操作。但是,您无法使用查询时找到的任意名称执行此操作。如果您需要,最好不要删除PIVOT,只使用内部查询提供的名称和值列。

DECLARE @xml xml

SET @xml = N'<properties>
    <property>
        <name>DISMISS_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>SHOW_SETTING</name>
        <value>DEFAULT</value>
    </property>
    <property>
        <name>DEFAULT_SETTING</name>
        <value>DEFAULT</value>
    </property>
</properties>'

SELECT     [DISMISS_SETTING], [SHOW_SETTING], [DEFAULT_SETTING]
FROM       (
                SELECT     properties.property.value(N'./name[1]', N'nvarchar(MAX)') AS propertyName
                         , properties.property.value(N'./value[1]', N'nvarchar(MAX)') AS propertyValue
                FROM       @xml.nodes(N'/properties/property') AS properties(property)
           ) AS properties
           PIVOT (MIN(propertyValue) FOR propertyName IN ([DISMISS_SETTING], [SHOW_SETTING], [DEFAULT_SETTING])) AS settings

答案 3 :(得分:1)

我决定更新我现有的答案(只是为了好奇的替代品和教育目的)。我推了另一个以保留两个版本并保留跟踪改进的部件的可能性:

  1. 更新第一种方法 - 每列的顺序插入/更新(用法 游标,删除冗余临时表):

    create procedure mysp_update (@table_name nvarchar(50), @column_name nvarchar(50), @column_value nvarchar(50))
    as
    begin
        set nocount on;
        declare @rows_count int
        declare @query nvarchar(500)
        declare @parm_definition nvarchar(100) = N'@column_value nvarchar(50)'        
    
        -- Update the row if it exists
        set @query = N'update ' + quotename(@table_name) + N'set ' + quotename(@column_name) + N' = @column_value'   
        exec sp_executesql @query, @parm_definition, @column_value = @column_value        
        -- Insert the row if the update statement failed
        if (@@rowcount = 0)
        begin
            set @query = N'insert into ' + quotename(@table_name) + N'(' + quotename(@column_name) + N') values (@column_value)'  
            exec sp_executesql @query, @parm_definition, @column_value = @column_value
        end
    end
    go
    
    create procedure mysp_xml_update (@table_name nvarchar(50), @data xml)
    as
    begin
        set nocount on;             
        declare @name nvarchar(50), @value nvarchar(50)
    
        -- Declare optimized cursor (fast_forward specifies forward_only, read_only cursor with performance optimizations enabled)
        declare mycursor cursor fast_forward
        for select
            x.value(N'(name)[1]', N'nvarchar(50)'),
            x.value(N'(value)[1]', N'nvarchar(50)')
        from
            @data.nodes(N'/properties/property') AS xtbl(x)
    
            open mycursor
            fetch next from mycursor into @name, @value 
            while @@fetch_status = 0
            begin       
                -- Execute SP here (btw: SP cannot be executed from select statement)
                exec mysp_update @table_name, @name, @value        
                -- Get the next row
                fetch next from mycursor into @name, @value
            end 
        close mycursor;
        deallocate mycursor;
    end
    go
    
  2. 更新第二种方法 - 批量插入/更新:

    create procedure mysp_xml_update (@table_name nvarchar(50), @data xml)
    as
    begin
        set nocount on;             
        declare @name nvarchar(50), @value nvarchar(50)
    
        -- Declare optimized cursor (fast_forward specifies forward_only, read_only cursor with performance optimizations enabled)
        declare mycursor cursor fast_forward
        for select
            x.value(N'(name)[1]', N'nvarchar(50)'),
            x.value(N'(value)[1]', N'nvarchar(50)')
        from
            @data.nodes(N'/properties/property') AS xtbl(x)
    
        declare @insert_statement nvarchar(max) = N'insert into ' + quotename(@table_name) + N' ($columns$) values (''$values$)'
        declare @update_statement nvarchar(max) = N'update ' + quotename(@table_name) + N' set $column$=''$value$'
    
        open mycursor
        fetch next from mycursor into @name, @value 
        while @@fetch_status = 0
        begin               
            set @insert_statement = replace(@insert_statement, '$columns$', quotename(@name) + ',$columns$')
            set @insert_statement = replace(@insert_statement, '$values$', @value + ''',''$values$')
            set @update_statement = replace(@update_statement, '$column$', quotename(@name))
            set @update_statement = replace(@update_statement, '$value$', @value + ''',$column$=''$value$')
            fetch next from mycursor into @name, @value
        end
        close mycursor;
        deallocate mycursor;
    
        set @insert_statement = replace(@insert_statement, ',$columns$', '')
        set @insert_statement = replace(@insert_statement, ',''$values$', '')
        set @update_statement = replace(@update_statement, ',$column$=''$value$', '')
    
        -- Update the row if it exists  
        exec sp_executesql @update_statement      
        -- Insert the row if the update statement failed
        if (@@rowcount = 0)
        begin          
            exec sp_executesql @insert_statement
        end
    end
    go
    
  3. 最终,全新的第三种方法(动态批量合并与数据透视,无循环,无游标):

    create procedure mysp_xml_update (@table_name nvarchar(50), @data xml)
    as
    begin
        set nocount on;     
        declare @columns nvarchar(max), @scolumns nvarchar(max), @kvp nvarchar(max)='', @query nvarchar(max)
        select @columns = coalesce(@columns + ',', '') + quotename(x.value(N'(name)[1]', N'nvarchar(50)')),
               @scolumns = coalesce(@scolumns + ',', '') + 's.' + quotename(x.value(N'(name)[1]', N'nvarchar(50)')),
               @kvp = @kvp + quotename(x.value(N'(name)[1]', N'nvarchar(50)')) + '=s.' 
                           + quotename(x.value(N'(name)[1]', N'nvarchar(50)')) + ','
        from @data.nodes(N'/properties/property') as xtbl(x)   
        select @kvp = left(@kvp, len(@kvp)-1)
    
        set @query = '
    merge ' + quotename(@table_name) + ' t
    using 
    (
        select ' + @columns + ' from 
        (
            select props.x.value(N''./name[1]'', N''nvarchar(50)'') as name,
                   props.x.value(N''./value[1]'', N''nvarchar(50)'') as value
            from @data.nodes(N''/properties/property'') as props(x)
        ) properties
        pivot 
        (
            min(value) for name in (' + @columns + ')
        ) settings
    ) s (' + @columns + ')
    on (1=1)
    when matched then 
        update set ' + @kvp + '
    when not matched then
        insert (' + @columns + ') 
        values (' + @scolumns + ');'    
    
        exec sp_executesql @query, N'@data xml', @data = @data
    end
    go              
    
  4. 用法如下:

    exec mysp_xml_update N'mytable', N'<properties>
                                           <property>
                                               <name>DEFAULT_SETTING</name>
                                               <value>NEW DEFAULT 3</value>
                                           </property>
                                           <property>
                                               <name>SHOW_SETTING</name>
                                               <value>NEW DEFAULT 2</value>
                                           </property>
                                       </properties>'