Question

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。

Answer 1

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

Answer 2

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值：

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

Answer 3

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

Answer 4

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：

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

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

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

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>'

使用T-SQL和XQUERY解析XML - 搜索特定值

4 个答案: