diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 73fb6fb64c44b0d0be890787fdb0197c3648cbd3..5b1216a21338f5d660014027d8c3bbdd084c24a1 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -1885,6 +1885,7 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
   const char* msg7 = "normal table can not apply this function";
   const char* msg8 = "multi-columns selection does not support alias column name";
   const char* msg9 = "invalid function";
+  const char* msg10 = "diff can no be applied to unsigned numeric type";
 
   switch (optr) {
     case TK_COUNT: {
@@ -2012,6 +2013,7 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
       if ((getColumnIndexByName(pCmd, &pParamElem->pNode->colInfo, pQueryInfo, &index) != TSDB_CODE_SUCCESS)) {
         return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg3);
       }
+
       if (index.columnIndex == TSDB_TBNAME_COLUMN_INDEX) {
         return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg6);
       }
@@ -2023,6 +2025,8 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
 
       if (!IS_NUMERIC_TYPE(colType)) {
         return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
+      } else if (IS_UNSIGNED_NUMERIC_TYPE(colType) && optr == TK_DIFF) {
+        return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg10);
       }
 
       int16_t resultType = 0;