Add : SqlFunc.Subqueryable<Order>().DistinctCount(z=>z.Id)

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/Items/SubDistinctCount.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+
+namespace SqlSugar
+{
+    public class SubDistinctCount : ISubOperation
+    {
+        public bool HasWhere
+        {
+            get; set;
+        }
+
+        public string Name
+        {
+            get
+            {
+                return "DistinctCount";
+            }
+        }
+
+        public Expression Expression
+        {
+            get; set;
+        }
+
+
+        public int Sort
+        {
+            get
+            {
+                return 200;
+            }
+        }
+
+        public ExpressionContext Context
+        {
+            get; set;
+        }
+
+        public string GetValue(Expression expression = null)
+        {
+            var exp = expression as MethodCallExpression;
+            var argExp = exp.Arguments[0];
+            var parametres = (argExp as LambdaExpression).Parameters;
+            if ((argExp as LambdaExpression).Body is UnaryExpression)
+            {
+                argExp = ((argExp as LambdaExpression).Body as UnaryExpression).Operand;
+            }
+            var argLambda = argExp as LambdaExpression;
+            if (this.Context.InitMappingInfo != null && argLambda != null && argLambda.Parameters.Count > 0)
+            {
+                foreach (var item in argLambda.Parameters)
+                {
+                    this.Context.InitMappingInfo(item.Type);
+                }
+                this.Context.RefreshMapping();
+            }
+            var result = "COUNT(DISTINCT " + SubTools.GetMethodValue(Context, argExp, ResolveExpressType.WhereMultiple) + ")";
+            var selfParameterName = Context.GetTranslationColumnName(parametres.First().Name) + UtilConstants.Dot;
+            result = result.Replace(selfParameterName, SubTools.GetSubReplace(this.Context));
+            return result;
+        }
+    }
+}

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/SubTools.cs

@@ -36,7 +36,8 @@ namespace SqlSugar
                                                     new SubHaving(){  Context=Context},
                                                     new SubWithNolock(){ Context=Context },
                                                     new SubEnableTableFilter(){ Context=Context },
-                                                    new SubSelectStringJoin{ Context=Context }
+                                                    new SubSelectStringJoin{ Context=Context },
+                                                    new SubDistinctCount{ Context=Context }
                                                 };
         }
 

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/Subquerable.cs

@@ -120,6 +120,11 @@ namespace SqlSugar
         {
             return default(string);
         }
+
+        public int DistinctCount(Func<T, object> expression) 
+        {
+            return default(int);
+        }
         public TResult Sum<TResult>(Func<T, TResult> expression) where TResult : struct
         {
             return default(TResult);

Src/Asp.Net/SqlSugar/SqlSugar.csproj

@@ -127,6 +127,7 @@
     <Compile Include="Entities\DeleteNavOptions.cs" />
     <Compile Include="Entities\JoinInfoParameter.cs" />
     <Compile Include="ExpressionsToSql\Common\NewExpressionInfo.cs" />
+    <Compile Include="ExpressionsToSql\Subquery\Items\SubDistinctCount.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubSelectStringJoin.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubWithNoLock.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubEnableTableFilter.cs" />