diff --git a/src/rootserver/ob_ddl_service.cpp b/src/rootserver/ob_ddl_service.cpp
index 9c68374e2f..c22a0b224b 100755
--- a/src/rootserver/ob_ddl_service.cpp
+++ b/src/rootserver/ob_ddl_service.cpp
@@ -8039,7 +8039,17 @@ int ObDDLService::modify_generated_column_local_vars(ObColumnSchemaV2 &generated
         ObExprResType dst_type;
         dst_type.set_meta(generated_column.get_meta_type());
         dst_type.set_accuracy(generated_column.get_accuracy());
-        if (OB_FAIL(ObRawExprUtils::erase_operand_implicit_cast(expr, expr))) {
+        ObSQLMode sql_mode = default_session.get_sql_mode();
+        if (NULL != local_session_var) {
+          share::schema::ObSessionSysVar *sys_var = NULL;
+          if (OB_FAIL(local_session_var->get_local_var(share::SYS_VAR_SQL_MODE, sys_var))) {
+            LOG_WARN("fail to get sys var", K(ret));
+          } else if (NULL != sys_var) {
+            sql_mode = sys_var->val_.get_uint64();
+          }
+        }
+        if (OB_FAIL(ret)) {
+        } else if (OB_FAIL(ObRawExprUtils::erase_operand_implicit_cast(expr, expr))) {
           LOG_WARN("erase implicit cast failed", K(ret));
         } else if (OB_ISNULL(expr)) {
           ret = OB_ERR_UNEXPECTED;
@@ -8061,7 +8071,7 @@ int ObDDLService::modify_generated_column_local_vars(ObColumnSchemaV2 &generated
                                                                               OB_INVALID_INDEX_INT64))) {
           LOG_WARN("expr formalize failed", K(ret));
         } else if (OB_FAIL(ObRawExprUtils::extract_local_vars_for_gencol(expr_with_implicit_cast,
-                                                                         default_session.get_sql_mode(),
+                                                                         sql_mode,
                                                                          generated_column))) {
           LOG_WARN("extract sysvar from expr failed", K(ret));
         }
diff --git a/src/sql/resolver/expr/ob_raw_expr_util.cpp b/src/sql/resolver/expr/ob_raw_expr_util.cpp
index aec2dd5738..9a11bf36bf 100644
--- a/src/sql/resolver/expr/ob_raw_expr_util.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr_util.cpp
@@ -9080,10 +9080,16 @@ int ObRawExprUtils::extract_local_vars_for_gencol(ObRawExpr *expr,
     }
     if (has_char_dep_col) {
       //add sql mode
-      ObSessionSysVar *local_var = NULL;
-      if (OB_FAIL(gen_col.get_local_session_var().get_local_var(SYS_VAR_SQL_MODE, local_var))) {
-        LOG_WARN("get local var failed", K(ret));
-      } else if (NULL == local_var) {
+      bool is_sql_mode_solidified = false;
+      for (int64_t i = 0; OB_SUCC(ret) && !is_sql_mode_solidified && i < var_array.count(); ++i) {
+        if (OB_ISNULL(var_array.at(i))) {
+          ret = OB_ERR_UNEXPECTED;
+          LOG_WARN("unexpected null", K(ret));
+        } else if (share::SYS_VAR_SQL_MODE == var_array.at(i)->type_) {
+          is_sql_mode_solidified = true;
+        }
+      }
+      if (OB_SUCC(ret) && !is_sql_mode_solidified) {
         local_sql_mode.type_ = SYS_VAR_SQL_MODE;
         local_sql_mode.val_.set_uint64(sql_mode);
         if (OB_FAIL(var_array.push_back(&local_sql_mode))) {