Issue 308: Statement.getGeneratedKeys() now returns an empty result set if no key was generated.

h2/src/main/org/h2/command/CommandContainer.java

@@ -11,6 +11,7 @@ import org.h2.expression.Parameter;
 import org.h2.expression.ParameterInterface;
 import org.h2.result.ResultInterface;
 import org.h2.value.Value;
+import org.h2.value.ValueNull;
 
 /**
  * Represents a single SQL statements.
@@ -65,6 +66,7 @@ class CommandContainer extends Command {
     public int update() {
         recompileIfRequired();
         start();
+        session.setLastIdentity(ValueNull.INSTANCE);
         prepared.checkParameters();
         int updateCount = prepared.update();
         prepared.trace(startTime, updateCount);

h2/src/main/org/h2/command/dml/Merge.java

@@ -26,7 +26,6 @@ import org.h2.table.Table;
 import org.h2.util.New;
 import org.h2.util.StatementBuilder;
 import org.h2.value.Value;
-import org.h2.value.ValueLong;
 
 /**
  * This class represents the statement
@@ -82,7 +81,6 @@ public class Merge extends Prepared {
         session.getUser().checkRight(table, Right.INSERT);
         session.getUser().checkRight(table, Right.UPDATE);
         setCurrentRowNumber(0);
-        session.setLastIdentity(ValueLong.get(0));
         if (list.size() > 0) {
             count = 0;
             for (int x = 0, size = list.size(); x < size; x++) {

h2/src/main/org/h2/jdbc/JdbcConnection.java

@@ -1440,7 +1440,7 @@ public class JdbcConnection extends TraceObject implements Connection {
      * INTERNAL
      */
     ResultSet getGeneratedKeys(JdbcStatement stat, int id) {
-        getGeneratedKeys = prepareCommand("CALL SCOPE_IDENTITY()", getGeneratedKeys);
+        getGeneratedKeys = prepareCommand("SELECT SCOPE_IDENTITY() WHERE SCOPE_IDENTITY() IS NOT NULL", getGeneratedKeys);
         ResultInterface result = getGeneratedKeys.executeQuery(0, false);
         ResultSet rs = new JdbcResultSet(this, stat, result, id, false, true, false);
         return rs;

h2/src/main/org/h2/jdbc/JdbcStatement.java

@@ -657,8 +657,9 @@ public class JdbcStatement extends TraceObject implements Statement {
     }
 
     /**
-     * Return a result set that contains the last generated autoincrement key
-     * for this connection.
+     * Return a result set that contains the last generated auto-increment key
+     * for this connection, if there was one. If no key was generated by the
+     * last modification statement, then an empty result set is returned.
      *
      * @return the result set with one row and one column containing the key
      * @throws SQLException if this object is closed
@@ -710,7 +711,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls executeUpdate(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param autoGeneratedKeys ignored
@@ -734,7 +735,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls executeUpdate(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param columnIndexes ignored
@@ -758,7 +759,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls executeUpdate(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param columnNames ignored
@@ -782,7 +783,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls execute(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param autoGeneratedKeys ignored
@@ -806,7 +807,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls execute(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param columnIndexes ignored
@@ -830,7 +831,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     /**
      * Executes a statement and returns the update count.
      * This method just calls execute(String sql) internally.
-     * The method getGeneratedKeys only supports one column.
+     * The method getGeneratedKeys supports at most one columns and row.
      *
      * @param sql the SQL statement
      * @param columnNames ignored

h2/src/test/org/h2/test/jdbc/TestPreparedStatement.java

@@ -356,6 +356,9 @@ public class TestPreparedStatement extends TestBase {
         rs.next();
         byte[] data = rs.getBytes(1);
         assertEquals(16, data.length);
+        stat.execute("INSERT INTO TEST_UUID VALUES(random_UUID())");
+        rs = stat.getGeneratedKeys();
+        assertFalse(rs.next());
         stat.execute("DROP TABLE TEST_UUID");
     }
 
@@ -394,6 +397,10 @@ public class TestPreparedStatement extends TestBase {
         ResultSet rs = stat.getGeneratedKeys();
         rs.next();
         assertEquals(1, rs.getLong(1));
+        stat.execute("insert into test values(100)");
+        rs = stat.getGeneratedKeys();
+        rs.next();
+        assertEquals(100, rs.getLong(1));
         stat.execute("drop sequence seq");
         stat.execute("drop table test");
     }

h2/src/test/org/h2/test/jdbc/TestStatement.java

@@ -337,8 +337,7 @@ public class TestStatement extends TestBase {
         stat.execute("insert into test2(x) values(10), (11), (12)");
         stat.execute("merge into test1(x) key(x) values(5)");
         keys = stat.getGeneratedKeys();
-        keys.next();
-        assertEquals(0, keys.getInt(1));
+        assertFalse(keys.next());
         stat.execute("merge into test1(x) key(x) values(6)");
         keys = stat.getGeneratedKeys();
         keys.next();