从查询postgresql转换为linq C#
我想使用“groupby”和“string\u agg”来处理linq,但我无法从这个查询中找到引用从查询postgresql转换为linq C#,c#,postgresql,api,linq,asp.net-core,C#,Postgresql,Api,Linq,Asp.net Core,我想使用“groupby”和“string\u agg”来处理linq,但我无法从这个查询中找到引用 SELECT DISTINCT "TB_M_GROUP_EMP"."GROUP_ID" AS "ID", string_agg(Distinct "TB_M_EMPLOYEES"."EMP_NAME",',' order by "TB_M_EMPLOYEES"."
SELECT DISTINCT "TB_M_GROUP_EMP"."GROUP_ID" AS "ID",
string_agg(Distinct "TB_M_EMPLOYEES"."EMP_NAME",',' order by "TB_M_EMPLOYEES"."EMP_NAME" ) as "Employee Name"
FROM public."TB_M_GROUP_EMP", "TB_M_EMPLOYEES"
GROUP BY "TB_M_GROUP_EMP"."GROUP_ID";
还是这个代码
SELECT DISTINCT "TB_M_GROUP_EMP"."GROUP_ID" as "Group Id", array_agg(Distinct"TB_M_EMPLOYEES"."EMP_CODE" || ',' ||"TB_M_EMPLOYEES"."EMP_NAME"|| ',' ||"TB_M_EMPLOYEES"."EMP_EMAIL" ) as "Employees"
FROM public."TB_M_GROUP_EMP", "TB_M_EMPLOYEES"
GROUP BY "TB_M_GROUP_EMP"."GROUP_ID";
请帮助将此查询转换为linq C#,并提供linq的参考或文档
我尝试过使用这段代码,但它不是我想要的输出
groupEmployee
.GroupBy(e => new { e.GroupId, e.Employee }, (key, group) => new
{
Employee = key.Employee,
Employees = group.ToList()
})
示例表:
--------------
TB_M_EMPLOYEES
--------------
|EMP_ID|EMP_CODE|EMP_NAME|EMP_EMAIL|
------------------------------------
|1 |E0012 |Ali |@ali |
|2 |E0013 |AL |@al |
|3 |E0014 |Abi |@abi |
|4 |E0015 |Ad |@ad |
|5 |E0016 |Ea |@ea |
----------------------
TB_M_GROUP_EMP
----------------------
|Id|GROUP_ID|EMP_ID|
----------------------
|1 |1 |1 |
|2 |1 |2 |
|3 |1 |3 |
|4 |1 |4 |
|5 |1 |5 |
从上面的两张桌子。
我希望输出是这个底部的表
TB_M_GROUP_EMP
-----------------
|GROUP_ID|EMP|
-----------------
|1 |{"E0012,Ali,@ali","E0013,Al,@al","E0014,Abi,@abi","E0015,Ad,@ad","E0016,Ea,@ea"}|
谢谢。退房:
前
items.Aggregate((i,j)=>i+分隔符+j));
这可能不会产生相同的SQL语句-因此您可能必须优化性能。也许您可以使用LINQ键入:
var result =
from employee in groupEmployee
group employee by employee.GroupId into output
select output;
现在你有了结果。为了回答您的问题,我使用了以下文章:假设我们有以下模型:
公共类员工
{
public int EmployeeId{get;set;}
公共字符串代码{get;set;}
公共字符串名称{get;set;}
公共字符串电子邮件{get;set;}
}
公共类雇员组
{
公共int Id{get;set;}
public int GroupId{get;set;}
public int EmployeeId{get;set;}
}
请尝试以下方法:
var结果=组
.Join(员工,grp=>grp.EmployeeId,emp=>emp.EmployeeId,(集团,员工)=>
新的
{
group.GroupId,
employee.EmployeeId,
员工代码,
雇员姓名,
员工邮箱,
})
.GroupBy(res=>res.GroupId)
.选择(res=>new
{
GroupId=res.Key,
name=string.Join(“,”,res
.OrderBy(e=>e.Name)
。选择(e=>$“{e.Code},{e.Name},{e.Email}”))
})
.ToList();
然而,这里的另一个verson可能是(可能更接近您想要的输出):
var result=groups.GroupJoin(employees,grp=>grp.EmployeeId,emp=>emp.EmployeeId,
(grp、emp)=>新
{
grp.GroupId,
Names=string.Join(“,”,emp.Select(e=>$”{e.Code},{e.Name},{e.Email}”))
}).
GroupBy(e=>e.GroupId)
.ToList();
如果您希望为上述内容提供有序(按名称)版本,那么查询可能会变得更复杂一些:
var结果=组
.GroupJoin(员工、,
grp=>grp.EmployeeId,
emp=>emp.EmployeeId,
(grp、EMP)=>
{
var empsList=emps.ToList();
还新
{
grp.GroupId,
NamesCmp=empsList.Select(e=>e.Name).FirstOrDefault(),//这是订购所需的
Names=string.Join(“,”,empsList.Select(e=>$”{e.Code},{e.Name},{e.Email}”))
};
})
.GroupBy(e=>e.GroupId)
.选择(grp=>new
{
GroupId=grp.Key,
Items=grp.OrderBy(g=>g.NamesCmp)
.选择(g=>g.Names)
})
.ToList();
请注意,对于上述类型,最好使用真实类模型,而不是匿名类型。根据我的理解,您正在寻找以下解决方案。如果我错过了什么,请告诉我
var result = (from empRow in TB_M_EMPLOYEES.AsEnumerable()
join grpRow in TB_M_GROUP_EMP.AsEnumerable()
on empRow.Field<string>("EMP_ID") equals grpRow.Field<string>("EMP_ID")
select new
{
EMP_ID = empRow.Field<string>("EMP_ID"),
EMP_CODE = empRow.Field<string>("EMP_CODE"),
EMP_NAME = empRow.Field<string>("EMP_NAME"),
EMP_EMAIL = empRow.Field<string>("EMP_EMAIL"),
GROUP_ID = grpRow.Field<string>("GROUP_ID")
}).GroupBy(r => r.GROUP_ID)
.Select(rs => new
{
GroupId = rs.Key,
FinalNames = string.Join(",", rs
.Select(e => $"\"{e.EMP_CODE},{e.EMP_NAME},{e.EMP_EMAIL}\""))
});
var result=(来自TB_M_EMPLOYEES.AsEnumerable()中的empRow)
加入grpRow加入TB_M_GROUP_EMP.AsEnumerable()
在empRow.Field上(“EMP_ID”)等于grpRow.Field(“EMP_ID”)
选择新的
{
EMP_ID=empRow.Field(“EMP_ID”),
EMP_代码=empRow.Field(“EMP_代码”),
EMP_NAME=empRow.Field(“EMP_NAME”),
EMP_EMAIL=empRow.Field(“EMP_EMAIL”),
组ID=grpRow.字段(“组ID”)
}).GroupBy(r=>r.GROUP\u ID)
.选择(rs=>new
{
GroupId=rs.Key,
FinalNames=string.Join(“,”,rs
。选择(e=>$“\”{e.EMP\U代码}、{e.EMP\U名称}、{e.EMP\U电子邮件}\“”)
});
测试功能如下:
static void PostResSql()
{
DataTable TB_M_EMPLOYEES = new DataTable();
TB_M_EMPLOYEES.Columns.Add("EMP_ID");
TB_M_EMPLOYEES.Columns.Add("EMP_CODE");
TB_M_EMPLOYEES.Columns.Add("EMP_NAME");
TB_M_EMPLOYEES.Columns.Add("EMP_EMAIL");
DataTable TB_M_GROUP_EMP = new DataTable();
TB_M_GROUP_EMP.Columns.Add("Id");
TB_M_GROUP_EMP.Columns.Add("GROUP_ID");
TB_M_GROUP_EMP.Columns.Add("EMP_ID");
DataRow row = TB_M_EMPLOYEES.NewRow();
row[0] = "1";
row[1] = "E0012";
row[2] = "Ali";
row[3] = "@ali";
TB_M_EMPLOYEES.Rows.Add(row);
row = TB_M_EMPLOYEES.NewRow();
row[0] = "2";
row[1] = "E0013";
row[2] = "AL";
row[3] = "@al";
TB_M_EMPLOYEES.Rows.Add(row);
row = TB_M_EMPLOYEES.NewRow();
row[0] = "3";
row[1] = "E0014";
row[2] = "Abi";
row[3] = "@abi";
TB_M_EMPLOYEES.Rows.Add(row);
row = TB_M_EMPLOYEES.NewRow();
row[0] = "4";
row[1] = "E0015";
row[2] = "Ad";
row[3] = "@ad";
TB_M_EMPLOYEES.Rows.Add(row);
row = TB_M_EMPLOYEES.NewRow();
row[0] = "5";
row[1] = "E0016";
row[2] = "Ea";
row[3] = "@ea";
TB_M_EMPLOYEES.Rows.Add(row);
row = TB_M_GROUP_EMP.NewRow();
row[0] = "1";
row[1] = "1";
row[2] = "1";
TB_M_GROUP_EMP.Rows.Add(row);
row = TB_M_GROUP_EMP.NewRow();
row[0] = "2";
row[1] = "1";
row[2] = "2";
TB_M_GROUP_EMP.Rows.Add(row);
row = TB_M_GROUP_EMP.NewRow();
row[0] = "3";
row[1] = "1";
row[2] = "3";
TB_M_GROUP_EMP.Rows.Add(row);
row = TB_M_GROUP_EMP.NewRow();
row[0] = "4";
row[1] = "1";
row[2] = "4";
TB_M_GROUP_EMP.Rows.Add(row);
row = TB_M_GROUP_EMP.NewRow();
row[0] = "5";
row[1] = "1";
row[2] = "5";
TB_M_GROUP_EMP.Rows.Add(row);
var result = (from empRow in TB_M_EMPLOYEES.AsEnumerable()
join grpRow in TB_M_GROUP_EMP.AsEnumerable()
on empRow.Field<string>("EMP_ID") equals grpRow.Field<string>("EMP_ID")
select new
{
EMP_ID = empRow.Field<string>("EMP_ID"),
EMP_CODE = empRow.Field<string>("EMP_CODE"),
EMP_NAME = empRow.Field<string>("EMP_NAME"),
EMP_EMAIL = empRow.Field<string>("EMP_EMAIL"),
GROUP_ID = grpRow.Field<string>("GROUP_ID")
}).GroupBy(r => r.GROUP_ID)
.Select(rs => new
{
GroupId = rs.Key,
FinalNames = string.Join(",", rs
.Select(e => $"\"{e.EMP_CODE},{e.EMP_NAME},{e.EMP_EMAIL}\""))
});
}
static void PostResSql()
{
DataTable TB_M_EMPLOYEES=新DataTable();
TB_M_EMPLOYEES.Columns.Add(“EMP_ID”);
TB_M_EMPLOYEES.Columns.Add(“EMP_代码”);
TB_M_EMPLOYEES.Columns.Add(“EMP_NAME”);
TB_M_EMPLOYEES.Columns.Add(“EMP_电子邮件”);
DataTable TB_M_GROUP_EMP=新DataTable();
TB_M_GROUP_EMP.Columns.Add(“Id”);
TB_M_GROUP_EMP.Columns.Add(“GROUP_ID”);
TB_M_GROUP_EMP.Columns.Add(“EMP_ID”);
DataRow row=TB_M_EMPLOYEES.NewRow();
行[0]=“1”;
行[1]=“E0012”;
第[2]行=“阿里”;
第[3]行=“@ali”;
TB_M_EMPLOYEES.Rows.Add(row);
row=TB_M_EMPLOYEES.NewRow();
行[0]=“2”;
行[1]=“E0013”;
行[2]=“AL”;
第[3]行=“@al”;
TB_M_EMPLOYEES.Rows.Add(row);
row=TB_M_EMPLOYEES.NewRow();
行[0]=“3”;
行[1]=“E0014”;
行[2]=“Abi”;
第[3]行=“@abi”;
TB_M_EMPLOYEES.Rows.Add(row);
row=TB_M_EMPLOYEES.NewRow();
行[0]=“4”;
行[1]=“E0015”;
行[2]=“Ad”;
第[3]行=“@ad”;
TB_M_EMPLOYEES.Rows.Add(row);
row=TB_M_EMPLOYEES.NewRow();
行[0]=“5”;
行[1]=“E0016”;
行[2]=“Ea”;
第[3]行=“@ea”;
TB_M_EMPLOYEES.Rows.Add(row);
row=TB_M_GROUP_EMP.NewRow();
行[0]=“1”;
行[1]=“1”;
行[2]=“1”;
TB_M_组_EMP.Rows.Add(row);
row=TB_M_GROUP_EMP.NewRow();
行[0]=“2”;
行[1]=“1”;
行[2]=“2”;
TB_M_组_EMP.Rows.Add(row);
row=TB_M_GROUP_EMP.NewRow();
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