使用xml 和merge 维护表数据的代码生成脚本

现在使用数据库来写存储过程，动不动参数就会用到xml ，当然罗，优势也很明显，参数相对固定，而且灵活，如果要修改或者什么的，中间接口层也不需要做变化，只需要修改封装的存储过程以及程序传参就ok了。

随着时间慢慢过，有时候就有一个存储过程，一个xml 来应对整个表的新增，修改，删除的情况了。而对于这个情况，我个人比较喜欢使用 Merge关键字来处理。但是如果表里面的列很多，那么复制黏贴啊之类的机械动作就会很多，而且没有什么价值。所以我就写了一个小脚本，应对了使用xml 来做表的增删改的作用首先我先创建一个表

CREATE TABLE employee(
ID INT IDENTITY(1,1) PRIMARY KEY,name NVARCHAR(50),age INT,birthdate DATE,salary MONEY
)

DECLARE @TableName VARCHAR(50) = 'employee',@XMLType TINYINT = 1,--1 使用with 格式,2 使用nodes 格式        
        @Path NVARCHAR(max) = 'root/employee',@HasAction BIT = 1 --0 没有动作 1 包含动作        

DECLARE @Columns NVARCHAR(MAX),--通用列的串
        @FilterColumns NVARCHAR(max),--过滤外键，主键的列
        @On NVARCHAR(100),--自动生成主键去匹配
        @Sql NVARCHAR(MAX)

SELECT @Columns = STUFF((
SELECT ',' + name
    FROM sys.columns 
        WHERE object_id = OBJECT_ID(@TableName)
        ORDER BY column_id
        FOR XML PATH('')),1,''),@FilterColumns = STUFF((
SELECT ',' + name
    FROM sys.columns 
        WHERE object_id = OBJECT_ID(@TableName)
           AND is_computed = 0
              AND is_identity = 0               
        ORDER BY column_id
        FOR XML PATH('')),@On = STUFF((
SELECT 'AND TAR.' + c.name + ' = SOUR.' + c.name
    FROM sys.indexes a
        INNER JOIN sys.index_columns b ON a.object_id = b.object_id 
        INNER JOIN sys.columns c ON c.object_id = b.object_id AND b.column_id = c.column_id
    WHERE a.object_id = OBJECT_ID(@TableName)
      AND a.is_primary_key = 1),4,'')

    

SELECT @Sql = ';WITH SOUR AS(
SELECT '+ CASE WHEN @XMLType = 1 THEN REPLACE(@Columns,',CHAR(10) + REPLICATE(CHAR(9),2) + ',') 
               WHEN @XMLType = 2 THEN STUFF((SELECT CHAR(10) + ',t.c.value(''(' + a.name + '/text())[1]'',''' + TYPE_NAME(user_type_id) +  CASE WHEN a.system_type_id IN (167,175) THEN '(' + CASE WHEN a.max_length = -1 THEN 'max' ELSE RTRIM(a.max_length) END+ ')'
                         WHEN a.system_type_id IN (231,239) THEN '(' + CASE WHEN a.max_length = -1 THEN 'max' ELSE RTRIM(a.max_length/2) END + ')'
                         WHEN a.system_type_id IN (59,106,108) THEN '(' + RTRIM(a.max_length) + ',' + RTRIM(a.scale) + ')'
                         ELSE ''
                         END + ''') AS ' + a.name
                        FROM sys.columns a
                            WHERE object_id = OBJECT_ID(@TableName)
                            ORDER BY column_id
                            FOR XML PATH('')),2,'')    
          ELSE '' END
        + CASE WHEN @XMLType = 1 AND @HasAction = 1 THEN CHAR(10)+ REPLICATE(CHAR(9),[Action]' 
               WHEN @XMLType = 2 AND @HasAction = 1 THEN CHAR(10)+ REPLICATE(CHAR(9),t.c.value(''@Action'',''tinyint'') [Action]' 
          ELSE '' END 
    + '
    FROM ' + CASE @XMLType WHEN 1 THEN ' OPENXML(@XmlInt,''' + @Path + ''',3)
                    WITH(' + STUFF((SELECT CHAR(10)+ REPLICATE(CHAR(9),6) + ',' + a.name + ' ' + UPPER(b.name) + CASE WHEN a.system_type_id IN (167,175,231,239,108) THEN '(' + CASE WHEN a.max_length = -1 THEN 'MAX' ELSE  RTRIM(a.max_length) END + ')'
                                                                  WHEN a.system_type_id IN (59,108) THEN '(' + RTRIM(a.precision) + ',' + RTRIM(a.scale)+ ')'
                                                             ELSE '' END + ' ''' + a.name + ''''
                                FROM sys.columns a
                                    INNER JOIN sys.systypes b ON a.system_type_id = b.xtype AND b.status = 0
                                    WHERE object_id = OBJECT_ID(@TableName)
                                      AND a.is_computed = 0
                                      ORDER BY column_id
                                      FOR XML PATH ('')
                                      ),8,'') + 
                            + CASE WHEN @HasAction = 1 THEN CHAR(10)+ REPLICATE(CHAR(9),[Action] tinyint ''@Action'')' ELSE ')' END 
                            WHEN 2 THEN ' @' + @TableName + '.nodes('''+@Path+''') as t(c)'
                            ELSE '' END 
             + '),TAR AS( SELECT ' + REPLACE(@Columns,') + '
        FROM ' + @TableName + ')
MERGE TAR
USING SOUR
ON '+@On+'
WHEN NOT MATCHED ' + CASE WHEN @HasAction = 1 THEN ' AND SOUR.[Action] = 1 ' ELSE '' END + '
            THEN INSERT(' + @FilterColumns + ')' + CHAR(10) + REPLICATE(CHAR(9),5) + ' VALUES (SOUR.' + REPLACE(@FilterColumns,SOUR.') + ')
WHEN MATCHED ' + CASE WHEN @HasAction = 1 THEN ' AND SOUR.[Action] = 2 ' ELSE '' END + ' THEN UPDATE SET ' 
+ STUFF((    SELECT ',' + CHAR(10) + REPLICATE(CHAR(9),5) +  'TAR.[' + name + ']= SOUR.[' + name + ']'
        FROM sys.columns a
            WHERE object_id = OBJECT_ID(@TableName)
              AND is_computed = 0
              AND is_identity = 0
              AND NOT EXISTS(SELECT * FROM sys.foreign_key_columns WHERE parent_object_id = a.object_id AND parent_column_id = a.column_id)
                ORDER BY column_id
            FOR XML PATH('')
    ),6,'') + '
    '+ CASE WHEN @HasAction = 1 THEN ' WHEN MATCHED  AND SOUR.[Action] = 3 ' ELSE 
    'WHEN MATCHED BY SOURCE ' END + ' THEN Delete;'
PRINT @Sql

(因为偷懒，所以使用的openxml 里面的那个 sp_xml_preparedocument 这里我是没有写的)(*^__^*) 嘻嘻……

然后看下生成的情况，这个是使用xml.nodes 来生成的

;WITH SOUR AS(
SELECT t.c.value('(ID/text())[1]','int') AS ID,t.c.value('(name/text())[1]','nvarchar(50)') AS name,t.c.value('(age/text())[1]','int') AS age,t.c.value('(birthdate/text())[1]','date') AS birthdate,t.c.value('(salary/text())[1]','money') AS salary,t.c.value('@Action','tinyint') [Action]
    FROM  @employee.nodes('root/employee') as t(c)),TAR AS( SELECT ID,name,age,birthdate,salary
        FROM employee)
MERGE TAR
USING SOUR
ON TAR.ID = SOUR.ID
WHEN NOT MATCHED  AND SOUR.[Action] = 1 
            THEN INSERT(name,salary)
                     VALUES (SOUR.name,SOUR.age,SOUR.birthdate,SOUR.salary)
WHEN MATCHED  AND SOUR.[Action] = 2  THEN UPDATE SET     TAR.[name]= SOUR.[name],TAR.[age]= SOUR.[age],TAR.[birthdate]= SOUR.[birthdate],TAR.[salary]= SOUR.[salary]
     WHEN MATCHED  AND SOUR.[Action] = 3  THEN Delete;

xml.nodes

;WITH SOUR AS(
SELECT ID,salary,[Action]
    FROM  OPENXML(@XmlInt,'root/employee',3)
                    WITH(ID INT 'ID',name NVARCHAR(100) 'name',age INT 'age',birthdate DATE 'birthdate',salary MONEY 'salary',[Action] tinyint '@Action')),TAR.[salary]= SOUR.[salary]
     WHEN MATCHED  AND SOUR.[Action] = 3  THEN Delete;

openxml

恩~然后就可放进去执行啦~~

这里只是一个很基本的用法。有几点要说明的

1、Xml的名称我默认和表名一致，有需要请改动

2、On的匹配模型我是使用主键来进行对应

其它如果有什么问题请告诉我补充~

（编辑：李大同）

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