[英]EF Core 2.1 group by with skip and take
我當前正在通過IQueryable進行“分頁”,該IQueryable具有許多字段{Table1Id,Table1Label,IsActive,...},並且在IQueryable結果中可能存在多個PdcId的記錄,如下所示:
var result = from a in _entities.table1
join b in _entities.table2 on new { a.Table1Id, a.Table1LevelId } equals new { Table1Id = b.Table2Id, Table1LevelId = b.Table2LevelId }
join c in _entities.Table3 on a.Table1Id equals c.Table1Id into cc from ccc in cc.DefaultIfEmpty()
where a.Valide == true
select new MeteringPointDetailModel
{
Table1Id = a.Table1Id,
Table1Label = a.Label,
IsActive = a.IsActive,
Table3Label = ccc.Label,
};
我嘗試了這段代碼,但是當我看到使用sql profiler在sql中生成結果時,查詢正在運行,而不會停止! (生成多個sql查詢)。
var data = await result.Where(i => result.GroupBy(p => p.Table1Id)
.Select(t => t.Key)
.Skip(query.Page).Take(query.PageSize)
.Contains(i.Table1Id)).ToListAsync();
如果我想先按Table1Id分組,然后跳過並采用不同的Table1Id,該怎么辦。
例如:如果我的結果有兩個記錄,一個結果是#50,另一個結果是#51,如果我按50進行分頁,則不會得到記錄51,而我想要它。
那就是我為我所做的工作:
解決方案1
var dataTable1 = (from a in _entities.table1
where a.Valide == true
select new {...}).Skip(query.Page).Take(query.PageSize);
var result = from a in dataTable1
join b in _entities.table2 on new { a.Table1Id, a.Table1LevelId } equals new { Table1Id = b.Table2Id, Table1LevelId = b.Table2LevelId }
join c in _entities.Table3 on a.Table1Id equals c.Table1Id into cc from ccc in cc.DefaultIfEmpty()
select new MeteringPointDetailModel
{
Table1Id = a.Table1Id,
Table1Label = a.Label,
IsActive = a.IsActive,
Table3Label = ccc.Label,
};
var data = await result.ToListAsync();
解決方案2
var result = from a in _entities.table1
join b in _entities.table2 on new { a.Table1Id, a.Table1LevelId } equals new { Table1Id = b.Table2Id, Table1LevelId = b.Table2LevelId }
join c in _entities.Table3 on a.Table1Id equals c.Table1Id into cc from ccc in cc.DefaultIfEmpty()
where a.Valide == true
select new MeteringPointDetailModel
{
Table1Id = a.Table1Id,
Table1Label = a.Label,
IsActive = a.IsActive,
Table3Label = ccc.Label,
};
result = !string.IsNullOrWhiteSpace(query.Table3Label) ? result.Where(c => c.Table3Label.ToLower().Contains(query.Table3Label.ToLower())) : result;
var table1Ids = await result.OrderBy(p => p.Table1Id)
.Select(p => p.Table1Id).Distinct()
.Skip(query.Page).Take(query.PageSize)
.ToListAsync();
var data = await result.Where(p => table1Ids.Contains(p.Table1Id)).ToListAsync();
如果示例中指定的聯接表中有子句條件(搜索條件),則解決方案2更有用。
希望它會幫助某人。
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