diff --git a/Src/Asp.NetCore2/SqlSugar/OnlyCore/PartialExpressionContexts.cs b/Src/Asp.NetCore2/SqlSugar/OnlyCore/PartialExpressionContexts.cs
new file mode 100644
index 000000000..7e982b12b
--- /dev/null
+++ b/Src/Asp.NetCore2/SqlSugar/OnlyCore/PartialExpressionContexts.cs
@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace SqlSugar 
+{
+    public partial class PostgreSQLExpressionContext
+    {
+    }
+    public partial class DmExpressionContext
+    {
+    }
+    public partial class OracleExpressionContext
+    {
+    }
+}
diff --git a/Src/Asp.NetCore2/SqlSugar/Realization/PostgreSQL/SqlBuilder/PostgreSQLExpressionContext.cs b/Src/Asp.NetCore2/SqlSugar/Realization/PostgreSQL/SqlBuilder/PostgreSQLExpressionContext.cs
index e5244c40a..560a50a58 100644
--- a/Src/Asp.NetCore2/SqlSugar/Realization/PostgreSQL/SqlBuilder/PostgreSQLExpressionContext.cs
+++ b/Src/Asp.NetCore2/SqlSugar/Realization/PostgreSQL/SqlBuilder/PostgreSQLExpressionContext.cs
@@ -2,7 +2,7 @@
 using System.Linq; 
 namespace SqlSugar
 {
-    public class PostgreSQLExpressionContext : ExpressionContext, ILambdaExpressions
+    public partial class PostgreSQLExpressionContext : ExpressionContext, ILambdaExpressions
     {
         public SqlSugarProvider Context { get; set; }
         public PostgreSQLExpressionContext()