新建database project
新建concatenate class
using system;
using system.data;
using microsoft.sqlserver.server;
using system.data.sqltypes;
using system.io;
using system.text;
[serializable]
[sqluserdefinedaggregate(
format.userdefined, //use clr serialization to serialize the intermediate result
isinvarianttonulls = true, //optimizer property
isinvarianttoduplicates = false, //optimizer property
isinvarianttoorder = false, //optimizer property
maxbytesize = 8000) //maximum size in bytes of persisted value
]public class concatenate : ibinaryserialize
///
/// accumulate the next value, not if the value is null
///
///
public void accumulate(sqlstring value)
}///
/// merge the partially computed aggregate with this aggregate.
///
///
public void merge(concatenate other)
///
/// called at the end of aggregation, to return the results of the aggregation.
///
///
public sqlstring terminate()
return new sqlstring(output);
}public void read(binaryreader r)
public void write(binarywriter w)
}編譯 concatenate class
註冊aggregate.dll'
create assembly myagg from 'c:\aggregate.dll'
gocreate aggregate myagg (@input nvarchar(200)) returns nvarchar(max)
external name myagg.concatenate
其中：第乙個、第三個myagg 是程式集名稱
concatenate是類名
第二個myagg是聚合函式名稱
concatenate為類名
如果註冊失敗或執行前失敗（禁止在 .net framework 中執行使用者**。啟用 "clr enabled" 配置選項 ），先執行以下sql
exec sp_configure 'show advanced options', '1';
goreconfigure;
goexec sp_configure 'clr enabled', '1'
goreconfigure;
exec sp_configure 'show advanced options', '1';
go刪除註冊
drop aggregate myagg
然後到程式集中將其刪除
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