From e6fa71d1ccf39fb8ec887251fe776e36922a1234 Mon Sep 17 00:00:00 2001
From: diego Dupin <diego.dupin@mariadb.com>
Date: Wed, 22 Jun 2022 15:31:43 +0200
Subject: [PATCH] [CONJ-953] PreparedStatement.getGeneratedKeys() returns rows
 when no keys are generated in insert

---
 src/main/java/org/mariadb/jdbc/Statement.java  | 17 ++++++++++-------
 .../jdbc/integration/StatementTest.java        | 18 ++++++++++++++++++
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/mariadb/jdbc/Statement.java b/src/main/java/org/mariadb/jdbc/Statement.java
index 0d36bae2f..4ea666035 100644
--- a/src/main/java/org/mariadb/jdbc/Statement.java
+++ b/src/main/java/org/mariadb/jdbc/Statement.java
@@ -853,16 +853,19 @@ public ResultSet getGeneratedKeys() throws SQLException {
     }
 
     if (currResult instanceof OkPacket) {
+
       OkPacket ok = ((OkPacket) currResult);
-      List<String[]> insertIds = new ArrayList<>();
-      insertIds.add(new String[] {String.valueOf(ok.getLastInsertId())});
-      for (Completion result : results) {
-        if (result instanceof OkPacket) {
-          insertIds.add(new String[] {String.valueOf(((OkPacket) result).getLastInsertId())});
+      if (ok.getLastInsertId() != 0) {
+        List<String[]> insertIds = new ArrayList<>();
+        insertIds.add(new String[]{String.valueOf(ok.getLastInsertId())});
+        for (Completion result : results) {
+          if (result instanceof OkPacket) {
+            insertIds.add(new String[]{String.valueOf(((OkPacket) result).getLastInsertId())});
+          }
         }
+        String[][] ids = insertIds.toArray(new String[0][]);
+        return CompleteResult.createResultSet("insert_id", DataType.BIGINT, ids, con.getContext());
       }
-      String[][] ids = insertIds.toArray(new String[0][]);
-      return CompleteResult.createResultSet("insert_id", DataType.BIGINT, ids, con.getContext());
     }
 
     return new CompleteResult(new ColumnDefinitionPacket[0], new byte[0][], con.getContext());
diff --git a/src/test/java/org/mariadb/jdbc/integration/StatementTest.java b/src/test/java/org/mariadb/jdbc/integration/StatementTest.java
index 1a6e182cf..6b0aa02c7 100644
--- a/src/test/java/org/mariadb/jdbc/integration/StatementTest.java
+++ b/src/test/java/org/mariadb/jdbc/integration/StatementTest.java
@@ -49,6 +49,24 @@ public static void beforeAll2() throws SQLException {
     stmt.execute("FLUSH TABLES");
   }
 
+  @Test
+  public void ensureGetGeneratedKeysReturnsEmptyResult() throws SQLException {
+    Statement stmt = sharedConn.createStatement();
+    stmt.execute("CREATE TABLE IF NOT EXISTS key_test (id INT(11) NOT NULL)");
+    try (PreparedStatement ps = sharedConn.prepareStatement("INSERT INTO key_test(id) VALUES(5)", Statement.RETURN_GENERATED_KEYS)) {
+      ps.execute();
+      ResultSet rs = ps.getGeneratedKeys();
+      assertFalse(rs.next());
+    }
+    try (PreparedStatement ps = sharedConn.prepareStatement("UPDATE key_test set id=7 WHERE id=5", Statement.RETURN_GENERATED_KEYS)) {
+      ps.execute();
+      ResultSet rs = ps.getGeneratedKeys();
+      assertFalse(rs.next());
+    }
+
+    stmt.execute("DROP TABLE key_test");
+  }
+
   @Test
   public void longGeneratedId() throws SQLException {
     longGeneratedId(BigInteger.ONE);