[SPARK-54108][CONNECT] Revise execute* methods of SparkConnectStatement

sql/connect/client/jdbc/src/main/scala/org/apache/spark/sql/connect/client/jdbc/SparkConnectStatement.scala

@@ -19,6 +19,8 @@ package org.apache.spark.sql.connect.client.jdbc
 
 import java.sql.{Array => _, _}
 
+import org.apache.spark.sql.connect.client.SparkResult
+
 class SparkConnectStatement(conn: SparkConnectConnection) extends Statement {
 
   private var operationId: String = _
@@ -49,33 +51,51 @@ class SparkConnectStatement(conn: SparkConnectConnection) extends Statement {
   }
 
   override def executeQuery(sql: String): ResultSet = {
-    checkOpen()
-
-    val df = conn.spark.sql(sql)
-    val sparkResult = df.collectResult()
-    operationId = sparkResult.operationId
-    resultSet = new SparkConnectResultSet(sparkResult, this)
-    resultSet
+    val hasResultSet = execute(sql)
+    if (hasResultSet) {
+      assert(resultSet != null)
+      resultSet
+    } else {
+      throw new SQLException("The query does not produce a ResultSet.")
+    }
   }
 
   override def executeUpdate(sql: String): Int = {
-    checkOpen()
-
-    val df = conn.spark.sql(sql)
-    val sparkResult = df.collectResult()
-    operationId = sparkResult.operationId
-    resultSet = null
+    val hasResultSet = execute(sql)
+    if (hasResultSet) {
+      // user are not expected to access the result set in this case,
+      // we must close it to avoid memory leak.
+      resultSet.close()
+      throw new SQLException("The query produces a ResultSet.")
+    } else {
+      assert(resultSet == null)
+      getUpdateCount
+    }
+  }
 
-    // always return 0 because affected rows is not supported yet
-    0
+  private def hasResultSet(sparkResult: SparkResult[_]): Boolean = {
+    // suppose this works in most cases
+    sparkResult.schema.length > 0
   }
 
   override def execute(sql: String): Boolean = {
     checkOpen()
 
-    // always perform executeQuery and reture a ResultSet
-    executeQuery(sql)
-    true
+    // stmt can be reused to execute more than one queries,
+    // reset before executing new query
+    operationId = null
+    resultSet = null
+
+    val df = conn.spark.sql(sql)
+    val sparkResult = df.collectResult()
+    operationId = sparkResult.operationId
+    if (hasResultSet(sparkResult)) {
+      resultSet = new SparkConnectResultSet(sparkResult, this)
+      true
+    } else {
+      sparkResult.close()
+      false
+    }
   }
 
   override def getResultSet: ResultSet = {
@@ -123,8 +143,15 @@ class SparkConnectStatement(conn: SparkConnectConnection) extends Statement {
   override def setCursorName(name: String): Unit =
     throw new SQLFeatureNotSupportedException
 
-  override def getUpdateCount: Int =
-    throw new SQLFeatureNotSupportedException
+  override def getUpdateCount: Int = {
+    checkOpen()
+
+    if (resultSet != null) {
+      -1
+    } else {
+      0 // always return 0 because affected rows is not supported yet
+    }
+  }
 
   override def getMoreResults: Boolean =
     throw new SQLFeatureNotSupportedException

sql/connect/client/jdbc/src/test/scala/org/apache/spark/sql/connect/client/jdbc/SparkConnectStatementSuite.scala

@@ -0,0 +1,80 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.connect.client.jdbc
+
+import java.sql.{Array => _, _}
+
+import scala.util.Using
+
+import org.apache.spark.sql.connect.client.jdbc.test.JdbcHelper
+import org.apache.spark.sql.connect.test.{ConnectFunSuite, RemoteSparkSession, SQLHelper}
+
+class SparkConnectStatementSuite extends ConnectFunSuite with RemoteSparkSession
+  with JdbcHelper with SQLHelper {
+
+  override def jdbcUrl: String = s"jdbc:sc://localhost:$serverPort"
+
+  test("returned result set and update count of execute* methods") {
+    withTable("t1", "t2", "t3") {
+      withStatement { stmt =>
+        // CREATE TABLE
+        assert(!stmt.execute("CREATE TABLE t1 (id INT) USING Parquet"))
+        assert(stmt.getUpdateCount === 0)
+        assert(stmt.getResultSet === null)
+
+        var se = intercept[SQLException] {
+          stmt.executeQuery("CREATE TABLE t2 (id INT) USING Parquet")
+        }
+        assert(se.getMessage === "The query does not produce a ResultSet.")
+
+        assert(stmt.executeUpdate("CREATE TABLE t3 (id INT) USING Parquet") === 0)
+        assert(stmt.getResultSet === null)
+
+        // INSERT INTO
+        assert(!stmt.execute("INSERT INTO t1 VALUES (1)"))
+        assert(stmt.getUpdateCount === 0)
+        assert(stmt.getResultSet === null)
+
+        se = intercept[SQLException] {
+          stmt.executeQuery("INSERT INTO t1 VALUES (1)")
+        }
+        assert(se.getMessage === "The query does not produce a ResultSet.")
+
+        assert(stmt.executeUpdate("INSERT INTO t1 VALUES (1)") === 0)
+        assert(stmt.getResultSet === null)
+
+        // SELECT
+        assert(stmt.execute("SELECT id FROM t1"))
+        assert(stmt.getUpdateCount === -1)
+        Using.resource(stmt.getResultSet) { rs =>
+          assert(rs !== null)
+        }
+
+        Using.resource(stmt.executeQuery("SELECT id FROM t1")) { rs =>
+          assert(stmt.getUpdateCount === -1)
+          assert(rs !== null)
+        }
+
+        se = intercept[SQLException] {
+          stmt.executeUpdate("SELECT id FROM t1")
+        }
+        assert(se.getMessage === "The query produces a ResultSet.")
+      }
+    }
+  }
+}