我需要进行两个左连接并从这两个左连接中求和/计数数据。
首先我尝试了一个左连接（ValorEfetuado）。该表可能有数据，如果有数据，我需要对其求和。
这是带有一个左连接和它生成的选择的原始查询（我认为非常简单）
var query = from l in db.Lancamentos
join tl in db.TiposLancamentos on l.IDTipoLancamento equals tl.IDTipoLancamento
join ve in db.ValoresEfetuados on l.IDLancamento equals ve.IDLancamento into ve_leftjoin
from _ve in ve_leftjoin.DefaultIfEmpty()
where (l.Excluido == false && l.IDConta == IDConta)
group _ve by new
{
TipoLancamento = tl.Descricao,
DataVencimento = l.DataVencimento,
IDLancamento = l.IDLancamento,
IDConta = l.IDConta,
Valor = l.Valor
} into grupo
select new _LancamentoGrid
{
IDConta = grupo.Key.IDConta,
IDLancamento = grupo.Key.IDLancamento,
Descricao = grupo.Key.TipoLancamento,
Valor = grupo.Key.Valor,
DataVencimento = grupo.Key.DataVencimento,
ValorEfetuado = grupo.Sum(_vesum => _vesum.Valor == null ? 0 : _vesum.Valor),
};
那就是选择
SELECT
[GroupBy1].[K1] AS [IDLancamento],
[GroupBy1].[K2] AS [IDConta],
[GroupBy1].[K5] AS [Descricao],
[GroupBy1].[K3] AS [Valor],
[GroupBy1].[K4] AS [DataVencimento],
[GroupBy1].[A1] AS [C1]
FROM ( SELECT
[Filter2].[K1] AS [K1],
[Filter2].[K2] AS [K2],
[Filter2].[K3] AS [K3],
[Filter2].[K4] AS [K4],
[Filter2].[K5] AS [K5],
SUM([Filter2].[A1]) AS [A1]
FROM ( SELECT
[Filter1].[IDLancamento] AS [K1],
[Filter1].[IDConta] AS [K2],
[Filter1].[Valor] AS [K3],
[Filter1].[DataVencimento] AS [K4],
[Filter1].[Descricao] AS [K5],
CASE WHEN ([Extent3].[Valor] IS NULL) THEN cast(0 as decimal(18)) ELSE [Extent3].[Valor] END AS [A1]
FROM (SELECT [Extent1].[IDLancamento] AS [IDLancamento], [Extent1].[IDConta] AS [IDConta], [Extent1].[Valor] AS [Valor], [Extent1].[DataVencimento] AS [DataVencimento], [Extent2].[Descricao] AS [Descricao]
FROM [fin].[Lancamento] AS [Extent1]
INNER JOIN [fin].[TipoLancamento] AS [Extent2] ON [Extent1].[IDTipoLancamento] = [Extent2].[IDTipoLancamento]
WHERE 0 = [Extent1].[Excluido] ) AS [Filter1]
LEFT OUTER JOIN [fin].[ValorEfetuado] AS [Extent3] ON [Filter1].[IDLancamento] = [Extent3].[IDLancamento]
WHERE [Filter1].[IDConta] = @p__linq__0
) AS [Filter2]
GROUP BY [K1], [K2], [K3], [K4], [K5]
) AS [GroupBy1]
就是这样，分组和总和。现在问题来了。当我在查询中加入新的左连接并按它分组时，我得到了一个有效的恶魔查询。很大。并且是低效的。就像在这个例子中
var query = from l in db.Lancamentos
join tl in db.TiposLancamentos on l.IDTipoLancamento equals tl.IDTipoLancamento
join ve in db.ValoresEfetuados on l.IDLancamento equals ve.IDLancamento into ve_leftjoin
from _ve in ve_leftjoin.DefaultIfEmpty()
join ld in db.LancamentosDocumentos on l.IDLancamento equals ld.IDLancamento into ld_leftjoin
from _ld in ld_leftjoin.DefaultIfEmpty()
where (l.Excluido == false && l.IDConta == IDConta)
group new { _ve, _ld } by new
{
TipoLancamento = tl.Descricao,
DataVencimento = l.DataVencimento,
IDLancamento = l.IDLancamento,
IDConta = l.IDConta,
Valor = l.Valor
} into grupo
select new _LancamentoGrid
{
IDConta = grupo.Key.IDConta,
IDLancamento = grupo.Key.IDLancamento,
Descricao = grupo.Key.TipoLancamento,
Valor = grupo.Key.Valor,
DataVencimento = grupo.Key.DataVencimento,
ValorEfetuado = grupo.Sum(_vesum => _vesum._ve.Valor == null ? 0 : _vesum._ve.Valor),
QtdContaDocumento = grupo.Count(_ldcount => _ldcount._ld.IDLancamento != null)
};
这导致一个丑陋的巨大查询，简单的剂量返回我要求的
SELECT
[Project4].[IDLancamento] AS [IDLancamento],
[Project4].[IDConta] AS [IDConta],
[Project4].[Descricao] AS [Descricao],
[Project4].[Valor] AS [Valor],
[Project4].[DataVencimento] AS [DataVencimento],
[Project4].[C1] AS [C1],
[Project4].[C2] AS [C2]
FROM ( SELECT
[Project3].[IDLancamento] AS [IDLancamento],
[Project3].[IDConta] AS [IDConta],
[Project3].[Valor] AS [Valor],
[Project3].[DataVencimento] AS [DataVencimento],
[Project3].[Descricao] AS [Descricao],
[Project3].[C1] AS [C1],
(SELECT
COUNT(1) AS [A1]
FROM (SELECT [Extent9].[IDLancamento] AS [IDLancamento1], [Extent9].[IDConta] AS [IDConta], [Extent9].[Valor] AS [Valor1], [Extent9].[DataVencimento] AS [DataVencimento], [Extent10].[Descricao] AS [Descricao]
FROM [fin].[Lancamento] AS [Extent9]
INNER JOIN [fin].[TipoLancamento] AS [Extent10] ON [Extent9].[IDTipoLancamento] = [Extent10].[IDTipoLancamento]
LEFT OUTER JOIN [fin].[ValorEfetuado] AS [Extent11] ON [Extent9].[IDLancamento] = [Extent11].[IDLancamento]
WHERE 0 = [Extent9].[Excluido] ) AS [Filter4]
INNER JOIN [fin].[LancamentoDocumento] AS [Extent12] ON [Filter4].[IDLancamento1] = [Extent12].[IDLancamento]
WHERE ([Filter4].[IDConta] = @p__linq__0) AND (([Project3].[Descricao] = [Filter4].[Descricao]) OR (([Project3].[Descricao] IS NULL) AND ([Filter4].[Descricao] IS NULL))) AND ([Project3].[DataVencimento] = [Filter4].[DataVencimento]) AND ([Project3].[IDLancamento] = [Filter4].[IDLancamento1]) AND ([Project3].[IDConta] = [Filter4].[IDConta]) AND ([Project3].[Valor] = [Filter4].[Valor1]) AND ([Extent12].[IDLancamento] IS NOT NULL)) AS [C2]
FROM ( SELECT
[Project2].[IDLancamento] AS [IDLancamento],
[Project2].[IDConta] AS [IDConta],
[Project2].[Valor] AS [Valor],
[Project2].[DataVencimento] AS [DataVencimento],
[Project2].[Descricao] AS [Descricao],
(SELECT
SUM([Filter3].[A1]) AS [A1]
FROM ( SELECT
CASE WHEN ([Extent7].[Valor] IS NULL) THEN cast(0 as decimal(18)) ELSE [Extent7].[Valor] END AS [A1]
FROM [fin].[Lancamento] AS [Extent5]
INNER JOIN [fin].[TipoLancamento] AS [Extent6] ON [Extent5].[IDTipoLancamento] = [Extent6].[IDTipoLancamento]
LEFT OUTER JOIN [fin].[ValorEfetuado] AS [Extent7] ON [Extent5].[IDLancamento] = [Extent7].[IDLancamento]
LEFT OUTER JOIN [fin].[LancamentoDocumento] AS [Extent8] ON [Extent5].[IDLancamento] = [Extent8].[IDLancamento]
WHERE (0 = [Extent5].[Excluido]) AND ([Extent5].[IDConta] = @p__linq__0) AND (([Project2].[Descricao] = [Extent6].[Descricao]) OR (([Project2].[Descricao] IS NULL) AND ([Extent6].[Descricao] IS NULL))) AND ([Project2].[DataVencimento] = [Extent5].[DataVencimento]) AND ([Project2].[IDLancamento] = [Extent5].[IDLancamento]) AND ([Project2].[IDConta] = [Extent5].[IDConta]) AND ([Project2].[Valor] = [Extent5].[Valor])
) AS [Filter3]) AS [C1]
FROM ( SELECT
[Distinct1].[IDLancamento] AS [IDLancamento],
[Distinct1].[IDConta] AS [IDConta],
[Distinct1].[Valor] AS [Valor],
[Distinct1].[DataVencimento] AS [DataVencimento],
[Distinct1].[Descricao] AS [Descricao]
FROM ( SELECT DISTINCT
[Filter1].[IDLancamento2] AS [IDLancamento],
[Filter1].[IDConta] AS [IDConta],
[Filter1].[Valor2] AS [Valor],
[Filter1].[DataVencimento] AS [DataVencimento],
[Filter1].[Descricao] AS [Descricao]
FROM (SELECT [Extent1].[IDLancamento] AS [IDLancamento2], [Extent1].[IDConta] AS [IDConta], [Extent1].[Valor] AS [Valor2], [Extent1].[DataVencimento] AS [DataVencimento], [Extent2].[Descricao] AS [Descricao]
FROM [fin].[Lancamento] AS [Extent1]
INNER JOIN [fin].[TipoLancamento] AS [Extent2] ON [Extent1].[IDTipoLancamento] = [Extent2].[IDTipoLancamento]
LEFT OUTER JOIN [fin].[ValorEfetuado] AS [Extent3] ON [Extent1].[IDLancamento] = [Extent3].[IDLancamento]
WHERE 0 = [Extent1].[Excluido] ) AS [Filter1]
LEFT OUTER JOIN [fin].[LancamentoDocumento] AS [Extent4] ON [Filter1].[IDLancamento2] = [Extent4].[IDLancamento]
WHERE [Filter1].[IDConta] = @p__linq__0
) AS [Distinct1]
) AS [Project2]
) AS [Project3]
) AS [Project4]
两个查询的区别：
- 第二个有一个新的左连接_ld
- 第二个有 ... group new {_ve,_ld} by ... 而不是 ... group _ve by ...
- 最后，我进行计数操作，这就是我想做的事情 QtdContaDocumento = grupo.Count(_ldcount => _ldcount._ld.IDLancamento != null)
我认为我误解了实体中的左连接或分组。让它正常工作并不难