diff --git a/velox/exec/fuzzer/DuckQueryRunner.cpp b/velox/exec/fuzzer/DuckQueryRunner.cpp
index 7943d68f84acd..ee9f9ed163e84 100644
--- a/velox/exec/fuzzer/DuckQueryRunner.cpp
+++ b/velox/exec/fuzzer/DuckQueryRunner.cpp
@@ -428,20 +428,11 @@ std::optional<std::string> DuckQueryRunner::toSql(
 
 std::optional<std::string> DuckQueryRunner::toSql(
     const std::shared_ptr<const core::NestedLoopJoinNode>& joinNode) {
-  const auto& joinKeysToSql = [](auto keys) {
-    std::stringstream out;
-    for (auto i = 0; i < keys.size(); ++i) {
-      if (i > 0) {
-        out << ", ";
-      }
-      out << keys[i]->name();
-    }
-    return out.str();
-  };
-
   const auto& outputNames = joinNode->outputType()->names();
   std::stringstream sql;
 
+  sql << "SELECT " << folly::join(", ", outputNames);
+
   // Nested loop join without filter.
   VELOX_CHECK(
       joinNode->joinCondition() == nullptr,
diff --git a/velox/exec/fuzzer/PrestoQueryRunner.cpp b/velox/exec/fuzzer/PrestoQueryRunner.cpp
index 605841d48a161..d0dede8cbeb1c 100644
--- a/velox/exec/fuzzer/PrestoQueryRunner.cpp
+++ b/velox/exec/fuzzer/PrestoQueryRunner.cpp
@@ -643,20 +643,11 @@ std::optional<std::string> PrestoQueryRunner::toSql(
 
 std::optional<std::string> PrestoQueryRunner::toSql(
     const std::shared_ptr<const core::NestedLoopJoinNode>& joinNode) {
-  const auto& joinKeysToSql = [](auto keys) {
-    std::stringstream out;
-    for (auto i = 0; i < keys.size(); ++i) {
-      if (i > 0) {
-        out << ", ";
-      }
-      out << keys[i]->name();
-    }
-    return out.str();
-  };
-
   const auto& outputNames = joinNode->outputType()->names();
   std::stringstream sql;
 
+  sql << "SELECT " << folly::join(", ", outputNames);
+
   // Nested loop join without filter.
   VELOX_CHECK(
       joinNode->joinCondition() == nullptr,