GH-797: [JDBC] Fix PreparedStatement#execute for DML/DDL (#811)

## What's Changed

Instead of always obtaining a result set for queries issued via
PreparedStatement.execute(), we now inspect the dataset_schema
returned in ActionCreatePreparedStatementResult. If the schema has no
fields, we retrieve the update count instead. This aligns the return
value with the expectations of the JDBC API.

For such cases, the Arrow Flight SQL path now uses
CommandPreparedStatementUpdate instead of
CommandPreparedStatementQuery. This change mirrors the existing
approach in Statement.execute() and Statement.executeUpdate().

### Are these changes tested?

Yes

Closes #797.

Author: ennuite

flight/flight-sql-jdbc-core/src/main/java/org/apache/arrow/driver/jdbc/ArrowFlightMetaImpl.java

@@ -62,14 +62,17 @@ static Signature newSignature(final String sql, Schema resultSetSchema, Schema p
         parameterSchema == null
             ? new ArrayList<>()
             : ConvertUtils.convertArrowFieldsToAvaticaParameters(parameterSchema.getFields());
-
+    StatementType statementType =
+        resultSetSchema == null || resultSetSchema.getFields().isEmpty()
+            ? StatementType.IS_DML
+            : StatementType.SELECT;
     return new Signature(
         columnMetaData,
         sql,
         parameters,
         Collections.emptyMap(),
         null, // unnecessary, as SQL requests use ArrowFlightJdbcCursor
-        StatementType.SELECT);
+        statementType);
   }
 
   @Override
@@ -105,7 +108,8 @@ public ExecuteResult execute(
             preparedStatement, ((ArrowFlightConnection) connection).getBufferAllocator())
         .bind(typedValues);
 
-    if (statementHandle.signature == null) {
+    if (statementHandle.signature == null
+        || statementHandle.signature.statementType == StatementType.IS_DML) {
       // Update query
       long updatedCount = preparedStatement.executeUpdate();
       return new ExecuteResult(

flight/flight-sql-jdbc-core/src/test/java/org/apache/arrow/driver/jdbc/ArrowFlightPreparedStatementTest.java

@@ -20,6 +20,8 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.nio.charset.StandardCharsets;
 import java.sql.Connection;
@@ -83,6 +85,19 @@ public void testSimpleQueryNoParameterBinding() throws SQLException {
     }
   }
 
+  @Test
+  public void testSimpleQueryNoParameterBindingWithExecute() throws SQLException {
+    final String query = CoreMockedSqlProducers.LEGACY_REGULAR_SQL_CMD;
+    try (final PreparedStatement preparedStatement = connection.prepareStatement(query)) {
+      boolean isResultSet = preparedStatement.execute();
+      assertTrue(isResultSet);
+      final ResultSet resultSet = preparedStatement.getResultSet();
+      CoreMockedSqlProducers.assertLegacyRegularSqlResultSet(resultSet);
+      assertFalse(preparedStatement.getMoreResults());
+      assertEquals(-1, preparedStatement.getUpdateCount());
+    }
+  }
+
   @Test
   public void testQueryWithParameterBinding() throws SQLException {
     final String query = "Fake query with parameters";
@@ -174,6 +189,20 @@ public void testUpdateQuery() throws SQLException {
     }
   }
 
+  @Test
+  public void testUpdateQueryWithExecute() throws SQLException {
+    String query = "Fake update with execute";
+    PRODUCER.addUpdateQuery(query, /*updatedRows*/ 42);
+    try (final PreparedStatement stmt = connection.prepareStatement(query)) {
+      boolean isResultSet = stmt.execute();
+      assertFalse(isResultSet);
+      int updated = stmt.getUpdateCount();
+      assertEquals(42, updated);
+      assertFalse(stmt.getMoreResults());
+      assertEquals(-1, stmt.getUpdateCount());
+    }
+  }
+
   @Test
   public void testUpdateQueryWithParameters() throws SQLException {
     String query = "Fake update with parameters";