SQL2005CLR函数扩展-数据导出的实现详解

sqlserver数据导出到excel有很多种方法，比如dts、ssis、还可以用sql语句调用openrowset。我们这里开拓思路，用clr来生成excel文件，并且会考虑一些方便操作的细节。

下面我先演示一下我实现的效果，先看测试语句
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exec bulkcopytoxls 'select * from testtable' , 'd:/test' , 'testtable' ,- 1
/*
开始导出数据
文件 d:/test/testtable.0.xls, 共65534条 , 大小20 ,450,868 字节
文件 d:/test/testtable.1.xls, 共65534条 , 大小 20 ,101,773 字节
文件 d:/test/testtable.2.xls, 共65534条 , 大小 20 ,040,589 字节
文件 d:/test/testtable.3.xls, 共65534条 , 大小 19 ,948,925 字节
文件 d:/test/testtable.4.xls, 共65534条 , 大小 20 ,080,974 字节
文件 d:/test/testtable.5.xls, 共65534条 , 大小 20 ,056,737 字节
文件 d:/test/testtable.6.xls, 共65534条 , 大小 20 ,590,933 字节
文件 d:/test/testtable.7.xls, 共26002条 , 大小 8,419,533 字节
导出数据完成
-------
共484740条数据，耗时 23812ms
*/
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上面的bulkcopytoxls存储过程是自定的clr存储过程。他有四个参数：
第一个是sql语句用来获取数据集
第二个是文件保存的路径
第三个是结果集的名字，我们用它来给文件命名
第四个是限制单个文件可以保存多少条记录,小于等于0表示最多65534条。

前三个参数没有什么特别，最后一个参数的设置可以让一个数据集分多个excel文件保存。比如传统excel的最大容量是65535条数据。我们这里参数设置为-1就表示导出达到这个数字之后自动写下一个文件。如果你设置了比如100，那么每导出100条就会自动写下一个文件。

另外每个文件都可以输出字段名作为表头，所以单个文件最多容纳65534条数据。

用微软公开的biff8格式通过二进制流生成excel，服务器无需安装excel组件，而且性能上不会比sql自带的功能差，48万多条数据，150m，用了24秒完成。
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下面我们来看下clr代码。通过sql语句获取datareader，然后分批用biff格式来写xls文件。
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using system;
using system.data;
using system.data.sqlclient;
using system.data.sqltypes;
using microsoft.sqlserver.server;
public partial class storedprocedures
{
    /// <summary>
    /// 导出数据
    /// </summary>
    /// <param name="sql"></param>
    /// <param name="savepath"></param>
    /// <param name="tablename"></param>
    /// <param name="maxrecordcount"></param>
    [microsoft.sqlserver.server.sqlprocedure ]
    public static void bulkcopytoxls(sqlstring sql, sqlstring savepath, sqlstring tablename, sqlint32 maxrecordcount)
    {
         if (sql.isnull || savepath.isnull || tablename.isnull)
        {
            sqlcontext .pipe.send(" 输入信息不完整！" );
        }
        ushort _maxrecordcount = ushort .maxvalue-1;

        if (maxrecordcount.isnull == false && maxrecordcount.value < ushort .maxvalue&&maxrecordcount.value>0)
            _maxrecordcount = (ushort )maxrecordcount.value;

        exportxls(sql.value, savepath.value, tablename.value, _maxrecordcount);
    }

    /// <summary>
    /// 查询数据，生成文件
    /// </summary>
    /// <param name="sql"></param>
    /// <param name="savepath"></param>
    /// <param name="tablename"></param>
    /// <param name="maxrecordcount"></param>
    private static void exportxls(string sql, string savepath, string tablename, system.uint16 maxrecordcount)
    {

        if (system.io.directory .exists(savepath) == false )
        {
            system.io.directory .createdirectory(savepath);
        }

        using (sqlconnection conn = new sqlconnection ("context connection=true" ))
        {
            conn.open();
            using (sqlcommand command = conn.createcommand())
            {
                command.commandtext = sql;
                using (sqldatareader reader = command.executereader())
                {
                    int i = 0;
                    int totalcount = 0;
                    int tick = system.environment .tickcount;
                    sqlcontext .pipe.send(" 开始导出数据" );
                    while (true )
                    {
                        string filename = string .format(@"{0}/{1}.{2}.xls" , savepath, tablename, i++);
                        int iexp = write(reader, maxrecordcount, filename);
                        long size = new system.io.fileinfo (filename).length;
                        totalcount += iexp;
                        sqlcontext .pipe.send(string .format(" 文件{0}, 共{1} 条, 大小{2} 字节" , filename, iexp, size.tostring("###,###" )));
                        if (iexp < maxrecordcount) break ;
                    }
                    tick = system.environment .tickcount - tick;
                     sqlcontext .pipe.send(" 导出数据完成" );

                     sqlcontext .pipe.send("-------" );
                     sqlcontext .pipe.send(string .format(" 共{0} 条数据，耗时{1}ms" ,totalcount,tick));
                }
            }
        }

 
    }
    /// <summary>
    /// 写单元格
    /// </summary>
    /// <param name="writer"></param>
    /// <param name="obj"></param>
    /// <param name="x"></param>
    /// <param name="y"></param>
    private static void writeobject(excelwriter writer, object obj, system.uint16 x, system.uint16 y)
    {
        string type = obj.gettype().name.tostring();
        switch (type)
        {
            case "sqlboolean" :
            case "sqlbyte" :
            case "sqldecimal" :
            case "sqldouble" :
            case "sqlint16" :
            case "sqlint32" :
            case "sqlint64" :
            case "sqlmoney" :
            case "sqlsingle" :
                if (obj.tostring().tolower() == "null" )
                    writer.writestring(x, y, obj.tostring());
                else
                    writer.writenumber(x, y, convert .todouble(obj.tostring()));
                break ;
            default :
                writer.writestring(x, y, obj.tostring());
                break ;
        }
    }
    /// <summary>
    /// 写一批数据到一个excel 文件
    /// </summary>
    /// <param name="reader"></param>
    /// <param name="count"></param>
    /// <param name="filename"></param>
    /// <returns></returns>
    private static int write(sqldatareader reader, system.uint16 count, string filename)
    {
        int iexp = count;
        excelwriter writer = new excelwriter (filename);
        writer.beginwrite();
        for (system.uint16 j = 0; j < reader.fieldcount; j++)
        {
            writer.writestring(0, j, reader.getname(j));
        }
        for (system.uint16 i = 1; i <= count; i++)
        {
            if (reader.read() == false )
            {
                iexp = i-1;
                break ;
            }
            for (system.uint16 j = 0; j < reader.fieldcount; j++)
            {
                writeobject(writer, reader.getsqlvalue(j), i, j);
            }
        }
        writer.endwrite();
        return iexp;
    }

    /// <summary>
    /// 写excel 的对象
    /// </summary>
    public class excelwriter
    {
        system.io.filestream _wirter;
        public excelwriter(string strpath)
        {
            _wirter = new system.io.filestream (strpath, system.io.filemode .openorcreate);
        }
        /// <summary>
        /// 写入short 数组
        /// </summary>
        /// <param name="values"></param>
        private void _writefile(system.uint16 [] values)
        {
            foreach (system.uint16 v in values)
            {
                byte [] b = system.bitconverter .getbytes(v);
                _wirter.write(b, 0, b.length);
            }
        }
        /// <summary>
        /// 写文件头
        /// </summary>
        public void beginwrite()
        {
            _writefile(new system.uint16 [] { 0x809, 8, 0, 0x10, 0, 0 });
        }
        /// <summary>
        /// 写文件尾
        /// </summary>
        public void endwrite()
        {
            _writefile(new system.uint16 [] { 0xa, 0 });
            _wirter.close();
        }
        /// <summary>
        /// 写一个数字到单元格x,y
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <param name="value"></param>
        public void writenumber(system.uint16 x, system.uint16 y, double value)
        {
            _writefile(new system.uint16 [] { 0x203, 14, x, y, 0 });
            byte [] b = system.bitconverter .getbytes(value);
            _wirter.write(b, 0, b.length);
         }
        /// <summary>
        /// 写一个字符到单元格x,y
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <param name="value"></param>
        public void writestring(system.uint16 x, system.uint16 y, string value)
        {
            byte [] b = system.text.encoding .default.getbytes(value);
            _writefile(new system.uint16 [] { 0x204, (system.uint16 )(b.length + 8), x, y, 0, (system.uint16 )b.length });
            _wirter.write(b, 0, b.length);
        }
    }
};

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把上面代码编译为testexcel.dll，copy到服务器目录。然后通过如下sql语句部署存储过程。
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create assembly testexcelforsqlclr from 'd:/sqlclr/testexcel.dll' with permission_set = unsafe;
--
go
create proc dbo. bulkcopytoxls 
(  
    @sql nvarchar ( max ),
    @savepath nvarchar ( 1000),
    @tablename nvarchar ( 1000),
    @bathcount int
)    
as external name testexcelforsqlclr. storedprocedures. bulkcopytoxls

go

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当这项技术掌握在我们自己手中的时候，就可以随心所欲的来根据自己的需求定制。比如，我可以不要根据序号来分批写入excel，而是根据某个字段的值（比如一个表有200个城市的8万条记录）来划分为n个文件，而这个修改只要调整一下datareader的循环里面的代码就行了。