Oracle SubStr BUG

Src/Asp.Net/OracleTest/Demos/1_Query.cs

@@ -374,11 +374,12 @@ namespace OrmTest.Demo
         {
             var db = GetInstance();
             db.IgnoreColumns.Add("TestId", "Student");
-            db.Insertable<Student>( new Student() { Name="a" }).ExecuteCommand();
+            db.Insertable<Student>( new Student() { Name="abc" }).ExecuteCommand();
             var s1 = db.Queryable<Student>().Select(it => new  { Name = it.Name, Student = it }).ToList();
             var s2 = db.Queryable<Student>().Select(it => new { id = it.Id, w = new { x = it } }).ToList();
             var s3 = db.Queryable<Student>().Select(it => new { newid = it.Id }).ToList();
             var s4 = db.Queryable<Student>().Select(it => new { newid = it.Id, obj = it }).ToList();
+            var s44 = db.Queryable<Student>().Where(it=>it.Name.Substring(0,1)=="a").ToList();
             var s5 = db.Queryable<Student>().Select(it => new ViewModelStudent2 { Student = it, Name = it.Name }).ToList();
             var s6 = db.Queryable<Student, School>((st, sc) => new object[] {
               JoinType.Left,st.SchoolId==sc.Id

Src/Asp.Net/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs

@@ -45,6 +45,13 @@ namespace SqlSugar
             var parameter = model.Args[0];
             return string.Format(" to_timestamp({0},'0000-01-01 hh24:mi:ss') ", parameter.MemberName);
         }
+        public override string Substring(MethodCallExpressionModel model)
+        {
+            var parameter = model.Args[0];
+            var parameter2 = model.Args[1];
+            var parameter3 = model.Args[2];
+            return string.Format("SUBSTR({0},1 + {1},{2})", parameter.MemberName, parameter2.MemberName, parameter3.MemberName);
+        }
         public override string DateValue(MethodCallExpressionModel model)
         {
             var parameter = model.Args[0];