从IQueryOver获取计数，无需从DB加载行

拥有IQueryOver，我如何从它获取行计数，而无需从DB加载所有行？ QueryOver有RowCount（）方法，但如果基础查询有组或不同，它会丢弃它们。从IQueryOver获取计数，无需从DB加载行

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SQL genearted为QueryOver.RowCount（正如你看到它丢弃DISTINCT）：

exec sp_executesql N' 
SELECT count(*) as y0_ 
FROM dbo.OPR_STL_DCM this_ 
left outer join dbo.OPR_STL_LN_ITM lineitem1_ 
on 
this_.DCM_ID=lineitem1_.DCM_ID 
left outer join dbo.OPR_STL_DY_LN_ITM daylineite2_ 
on 
lineitem1_.DCM_ID=daylineite2_.DCM_ID and 
lineitem1_.TND_ID=daylineite2_.TND_ID 
WHERE 
daylineite2_.BSNS_DT >= @p0 and 
daylineite2_.BSNS_DT <= @p1' 
,N'@p0 datetime,@p1 datetime',@p0='2016-07-22 00:00:00',@p1='2016-08-21 23:59:59'

和

为生成的SQL QueryOver：

exec sp_executesql N' 
SELECT distinct this_.DCM_ID as y0_, 
    this_.RTL_STR_ID as y1_, 
    this_.WS_ID as y2_, 
    this_.BSNS_DT as y3_, 
    this_.OPR_ID as y4_, 
    this_.TND_RPSTY_ID as y5_, 
    this_.IS_CNC as y6_, 
    this_.IS_SNG_DY_STL as y7_, 
    this_.BGN_DT_TM as y8_, 
    this_.END_DT_TM as y9_ 
FROM dbo.OPR_STL_DCM this_ 
left outer join dbo.OPR_STL_LN_ITM lineitem1_ 
on 
this_.DCM_ID=lineitem1_.DCM_ID 
left outer join dbo.OPR_STL_DY_LN_ITM daylineite2_ 
on 
lineitem1_.DCM_ID=daylineite2_.DCM_ID and 
lineitem1_.TND_ID=daylineite2_.TND_ID 
WHERE daylineite2_.BSNS_DT >= @p1 and 
daylineite2_.BSNS_DT <= @p2' 
,N'@p1 datetime,@p2 datetime',@p0=20,@p1='2016-07-22 00:00:00',@p2='2016-08-21 23:59:59'

来源

2017-07-30 Saeed D.

正如你看到的，行数方法没有得到查询结果的实际计数！ –

最后，我找到了解决办法。注入MyMsSql2008Dialect为nhibernate.dialect值。该类将行数插入名为#TempCount的临时表中;现在你可以从#TempCount中读取行数。请注意，这必须在会话中完成。

public class MyMsSql2008Dialect : MsSql2008Dialect 
{ 
    public override SqlString GetLimitString(SqlString queryString, SqlString offset, SqlString limit) 
    { 
     SqlString limitString = base.GetLimitString(queryString, offset, limit); 

     SqlStringBuilder ssb = new SqlStringBuilder(); 

     string resultCountQuery = string.Format(
      @" 
       INSERT INTO #TempCount 
       SElECT COUNT(*) AS Count FROM 
       (
        {0} 
       ) AS _queryResult 
      " 
      , queryString); 

     ssb.Add(resultCountQuery); 

     SqlStringBuilder newLimitString = new SqlStringBuilder(); 
     newLimitString.Add(limitString).Add(Environment.NewLine).Add(ssb.ToSqlString()); 

     return newLimitString.ToSqlString(); 
    } 
}

而获得的行数：

int rowsCount = session.CreateSQLQuery("SELECT TOP 1 * FROM #TempCount").UniqueResult<int>();

来源

2017-08-26 12:34:43

我认为这不支持IQueryOver，但不要在此引用我。

我得到了它的ICriteria虽然工作..

crit.SetProjection(Projections.Count(Projections.Distinct(Projections.Id())));

来源

2017-08-03 11:53:34 JayRone

从IQueryOver获取计数，无需从DB加载行

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