diff --git a/contrib/dolphin/expected/test_condition.out b/contrib/dolphin/expected/test_condition.out
index 65ee7b38af3e5667e82af0ba7b0354a4d5a244b9..7644b3a145e1a993dada588ccbccbb604d63fffe 100644
--- a/contrib/dolphin/expected/test_condition.out
+++ b/contrib/dolphin/expected/test_condition.out
@@ -8537,6 +8537,30 @@ select strcmp(blb, txt) from typeset;
      -1
 (1 row)
 
+create table t1 (a int, b bigint unsigned);
+create table t2 (c int);
+insert into t1 (a, b) values (1,4572794622775114594), (2,18196094287899841997),
+(3,11120436154190595086);
+insert into t2 (c) values (1), (2), (3);
+select case t1.a when 0 then 0 else t1.b end from t1 order by a;
+          b           
+----------------------
+ 4572794622775114594
+ 18196094287899841997
+ 11120436154190595086
+(3 rows)
+
+select t1.a, (case t1.a when 0 then 0 else t1.b end) d from t1
+join t2 on t1.a=t2.c order by d;
+ a |          d           
+---+----------------------
+ 1 | 4572794622775114594
+ 3 | 11120436154190595086
+ 2 | 18196094287899841997
+(3 rows)
+
+drop table t1;
+drop table t2;
 drop schema db_test_condition cascade;
 NOTICE:  drop cascades to table typeset
 reset current_schema;
diff --git a/contrib/dolphin/include/plugin_parser/parse_oper.h b/contrib/dolphin/include/plugin_parser/parse_oper.h
index 492c68dabbeb415bfbb279d4f547fef0a7d17daa..57c4b058374e12a9b25b5cf7c58c442ac90e465f 100644
--- a/contrib/dolphin/include/plugin_parser/parse_oper.h
+++ b/contrib/dolphin/include/plugin_parser/parse_oper.h
@@ -50,11 +50,11 @@ extern Oid oprfuncid(Operator op);
 extern bool IsIntType(Oid typeoid);
 extern bool IsCharType(Oid typeoid);
 #ifdef DOLPHIN
-extern inline bool IsUnsignedIntType(Oid typeoid);
-extern inline bool IsFloatType(Oid typeoid);
-extern inline bool IsNumericType(Oid typeoid);
-extern inline bool IsDolphinStringType(Oid typeoid);
-extern inline bool IsDatetimeType(Oid typeoid);
+extern bool IsUnsignedIntType(Oid typeoid);
+extern bool IsFloatType(Oid typeoid);
+extern bool IsNumericType(Oid typeoid);
+extern bool IsDolphinStringType(Oid typeoid);
+extern bool IsDatetimeType(Oid typeoid);
 #endif
 
 /* Build expression tree for an operator invocation */
diff --git a/contrib/dolphin/plugin_parser/parse_coerce.cpp b/contrib/dolphin/plugin_parser/parse_coerce.cpp
index 0f3cb986aa4a9cbe4e395806d02d93614fb872b7..7db6d95d458c8246818ec43495eed7bc2221e9ab 100644
--- a/contrib/dolphin/plugin_parser/parse_coerce.cpp
+++ b/contrib/dolphin/plugin_parser/parse_coerce.cpp
@@ -31,6 +31,7 @@
 #include "plugin_parser/parse_relation.h"
 #include "plugin_parser/parse_type.h"
 #ifdef DOLPHIN
+#include "plugin_parser/parse_oper.h"
 #include "plugin_commands/mysqlmode.h"
 #endif
 #include "utils/builtins.h"
@@ -1934,7 +1935,15 @@ static Oid choose_specific_expr_type(ParseState* pstate, List* exprs, const char
         }
 
         preferType = getBaseType(exprType(preferExpr));
-        get_type_category_preferred(preferType, &preferCategory, &pispreferred);
+#ifdef DOLPHIN
+        if (IsUnsignedIntType(preferType)) {
+            preferCategory = 'N';
+            pispreferred = false;
+        } else
+#endif
+        {
+            get_type_category_preferred(preferType, &preferCategory, &pispreferred);
+        }
         break;
     }
     if (lc == NULL) {
@@ -1956,8 +1965,15 @@ static Oid choose_specific_expr_type(ParseState* pstate, List* exprs, const char
         if (nextType != preferType) {
             TYPCATEGORY nextCategory;
             bool nispreferred = false;
-
-            get_type_category_preferred(nextType, &nextCategory, &nispreferred);
+#ifdef DOLPHIN
+            if (IsUnsignedIntType(nextType)) {
+                nextCategory = 'N';
+                nispreferred = false;
+            } else
+#endif
+            {
+                get_type_category_preferred(nextType, &nextCategory, &nispreferred);
+            }
 
             /*
              * Both types in different categories, if they are numeric and string type
diff --git a/contrib/dolphin/sql/test_condition.sql b/contrib/dolphin/sql/test_condition.sql
index 7dc8df15341184f4940ceff6ae18b8070436d8ad..4cd9bbc20f6849105f03633fca126abc475fc44e 100644
--- a/contrib/dolphin/sql/test_condition.sql
+++ b/contrib/dolphin/sql/test_condition.sql
@@ -1285,8 +1285,16 @@ select strcmp(vch, blb) from typeset;
 select strcmp(vch, txt) from typeset;
 select strcmp(blb, txt) from typeset;
 
-
-
+create table t1 (a int, b bigint unsigned);
+create table t2 (c int);
+insert into t1 (a, b) values (1,4572794622775114594), (2,18196094287899841997),
+(3,11120436154190595086);
+insert into t2 (c) values (1), (2), (3);
+select case t1.a when 0 then 0 else t1.b end from t1 order by a;
+select t1.a, (case t1.a when 0 then 0 else t1.b end) d from t1
+join t2 on t1.a=t2.c order by d;
+drop table t1;
+drop table t2;
 
 drop schema db_test_condition cascade;
 reset current_schema;