diff --git a/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/DockerJDBCIntegrationSuite.scala b/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/DockerJDBCIntegrationSuite.scala
index 6d1a22dd22b65..24927da16d50c 100644
--- a/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/DockerJDBCIntegrationSuite.scala
+++ b/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/DockerJDBCIntegrationSuite.scala
@@ -98,7 +98,13 @@ abstract class DockerJDBCIntegrationSuite extends SharedSparkSession with Eventu
   val connectionTimeout = timeout(2.minutes)
 
   private var docker: DockerClient = _
-  protected var externalPort: Int = _
+  // Configure networking (necessary for boot2docker / Docker Machine)
+  protected lazy val externalPort: Int = {
+    val sock = new ServerSocket(0)
+    val port = sock.getLocalPort
+    sock.close()
+    port
+  }
   private var containerId: String = _
   protected var jdbcUrl: String = _
 
@@ -122,13 +128,6 @@ abstract class DockerJDBCIntegrationSuite extends SharedSparkSession with Eventu
           log.warn(s"Docker image ${db.imageName} not found; pulling image from registry")
           docker.pull(db.imageName)
       }
-      // Configure networking (necessary for boot2docker / Docker Machine)
-      externalPort = {
-        val sock = new ServerSocket(0)
-        val port = sock.getLocalPort
-        sock.close()
-        port
-      }
       val hostConfigBuilder = HostConfig.builder()
         .privileged(db.privileged)
         .networkMode("bridge")
diff --git a/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/OracleIntegrationSuite.scala b/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/OracleIntegrationSuite.scala
new file mode 100644
index 0000000000000..400459c0ea17b
--- /dev/null
+++ b/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/OracleIntegrationSuite.scala
@@ -0,0 +1,152 @@
+/*
+ * 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.jdbc.v2
+
+import java.sql.Connection
+
+import org.scalatest.time.SpanSugar._
+
+import org.apache.spark.SparkConf
+import org.apache.spark.sql.AnalysisException
+import org.apache.spark.sql.catalyst.parser.ParseException
+import org.apache.spark.sql.execution.datasources.v2.jdbc.JDBCTableCatalog
+import org.apache.spark.sql.jdbc.{DatabaseOnDocker, DockerJDBCIntegrationSuite}
+import org.apache.spark.sql.test.SharedSparkSession
+import org.apache.spark.sql.types._
+import org.apache.spark.tags.DockerTest
+
+/**
+ * The following would be the steps to test this
+ * 1. Build Oracle database in Docker, please refer below link about how to.
+ *    https://github.com/oracle/docker-images/blob/master/OracleDatabase/SingleInstance/README.md
+ * 2. export ORACLE_DOCKER_IMAGE_NAME=$ORACLE_DOCKER_IMAGE_NAME
+ *    Pull oracle $ORACLE_DOCKER_IMAGE_NAME image - docker pull $ORACLE_DOCKER_IMAGE_NAME
+ * 3. Start docker - sudo service docker start
+ * 4. Run spark test - ./build/sbt -Pdocker-integration-tests
+ *    "test-only org.apache.spark.sql.jdbc.v2.OracleIntegrationSuite"
+ *
+ * An actual sequence of commands to run the test is as follows
+ *
+ *  $ git clone https://github.com/oracle/docker-images.git
+ *  // Head SHA: 3e352a22618070595f823977a0fd1a3a8071a83c
+ *  $ cd docker-images/OracleDatabase/SingleInstance/dockerfiles
+ *  $ ./buildDockerImage.sh -v 18.4.0 -x
+ *  $ export ORACLE_DOCKER_IMAGE_NAME=oracle/database:18.4.0-xe
+ *  $ cd $SPARK_HOME
+ *  $ ./build/sbt -Pdocker-integration-tests
+ *    "test-only org.apache.spark.sql.jdbc.v2.OracleIntegrationSuite"
+ *
+ * It has been validated with 18.4.0 Express Edition.
+ */
+@DockerTest
+class OracleIntegrationSuite extends DockerJDBCIntegrationSuite with SharedSparkSession {
+  override val db = new DatabaseOnDocker {
+    override val imageName = sys.env("ORACLE_DOCKER_IMAGE_NAME")
+    override val env = Map(
+      "ORACLE_PWD" -> "oracle"
+    )
+    override val usesIpc = false
+    override val jdbcPort: Int = 1521
+    override def getJdbcUrl(ip: String, port: Int): String =
+      s"jdbc:oracle:thin:system/oracle@//$ip:$port/xe"
+  }
+
+  override def sparkConf: SparkConf = super.sparkConf
+    .set("spark.sql.catalog.oracle", classOf[JDBCTableCatalog].getName)
+    .set("spark.sql.catalog.oracle.url", db.getJdbcUrl(dockerIp, externalPort))
+
+  override val connectionTimeout = timeout(7.minutes)
+  override def dataPreparation(conn: Connection): Unit = {}
+
+  test("SPARK-33034: ALTER TABLE ... add new columns") {
+    withTable("oracle.alt_table") {
+      sql("CREATE TABLE oracle.alt_table (ID STRING) USING _")
+      sql("ALTER TABLE oracle.alt_table ADD COLUMNS (C1 STRING, C2 STRING)")
+      var t = spark.table("oracle.alt_table")
+      var expectedSchema = new StructType()
+        .add("ID", StringType)
+        .add("C1", StringType)
+        .add("C2", StringType)
+      assert(t.schema === expectedSchema)
+      sql("ALTER TABLE oracle.alt_table ADD COLUMNS (C3 STRING)")
+      t = spark.table("oracle.alt_table")
+      expectedSchema = expectedSchema.add("C3", StringType)
+      assert(t.schema === expectedSchema)
+      // Add already existing column
+      val msg = intercept[AnalysisException] {
+        sql(s"ALTER TABLE oracle.alt_table ADD COLUMNS (C3 DOUBLE)")
+      }.getMessage
+      assert(msg.contains("Cannot add column, because C3 already exists"))
+    }
+    // Add a column to not existing table
+    val msg = intercept[AnalysisException] {
+      sql(s"ALTER TABLE oracle.not_existing_table ADD COLUMNS (C4 STRING)")
+    }.getMessage
+    assert(msg.contains("Table not found"))
+  }
+
+  test("SPARK-33034: ALTER TABLE ... update column type") {
+    withTable("oracle.alt_table") {
+      sql("CREATE TABLE oracle.alt_table (ID INTEGER) USING _")
+      sql("ALTER TABLE oracle.alt_table ALTER COLUMN id TYPE STRING")
+      val t = spark.table("oracle.alt_table")
+      val expectedSchema = new StructType().add("ID", StringType)
+      assert(t.schema === expectedSchema)
+      // Update column type from STRING to INTEGER
+      val msg1 = intercept[AnalysisException] {
+        sql("ALTER TABLE oracle.alt_table ALTER COLUMN id TYPE INTEGER")
+      }.getMessage
+      assert(msg1.contains("Cannot update alt_table field ID: string cannot be cast to int"))
+      // Update not existing column
+      val msg2 = intercept[AnalysisException] {
+        sql("ALTER TABLE oracle.alt_table ALTER COLUMN bad_column TYPE DOUBLE")
+      }.getMessage
+      assert(msg2.contains("Cannot update missing field bad_column"))
+      // Update column to wrong type
+      val msg3 = intercept[ParseException] {
+        sql("ALTER TABLE oracle.alt_table ALTER COLUMN id TYPE bad_type")
+      }.getMessage
+      assert(msg3.contains("DataType bad_type is not supported"))
+    }
+    // Update column type in not existing table
+    val msg = intercept[AnalysisException] {
+      sql(s"ALTER TABLE oracle.not_existing_table ALTER COLUMN id TYPE DOUBLE")
+    }.getMessage
+    assert(msg.contains("Table not found"))
+  }
+
+  test("SPARK-33034: ALTER TABLE ... update column nullability") {
+    withTable("oracle.alt_table") {
+      sql("CREATE TABLE oracle.alt_table (ID STRING NOT NULL) USING _")
+      sql("ALTER TABLE oracle.alt_table ALTER COLUMN ID DROP NOT NULL")
+      val t = spark.table("oracle.alt_table")
+      val expectedSchema = new StructType().add("ID", StringType, nullable = true)
+      assert(t.schema === expectedSchema)
+      // Update nullability of not existing column
+      val msg = intercept[AnalysisException] {
+        sql("ALTER TABLE oracle.alt_table ALTER COLUMN bad_column DROP NOT NULL")
+      }.getMessage
+      assert(msg.contains("Cannot update missing field bad_column"))
+    }
+    // Update column nullability in not existing table
+    val msg = intercept[AnalysisException] {
+      sql(s"ALTER TABLE oracle.not_existing_table ALTER COLUMN ID DROP NOT NULL")
+    }.getMessage
+    assert(msg.contains("Table not found"))
+  }
+}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCTable.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCTable.scala
index 55759497bd910..5e11ea66be4c6 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCTable.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCTable.scala
@@ -30,7 +30,6 @@ import org.apache.spark.sql.util.CaseInsensitiveStringMap
 
 case class JDBCTable(ident: Identifier, schema: StructType, jdbcOptions: JDBCOptions)
   extends Table with SupportsRead with SupportsWrite {
-  assert(ident.namespace().length == 1)
 
   override def name(): String = ident.toString
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
index cea5a20917532..a01720d1eefc7 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
@@ -212,7 +212,7 @@ abstract class JdbcDialect extends Serializable {
         case add: AddColumn if add.fieldNames.length == 1 =>
           val dataType = JdbcUtils.getJdbcType(add.dataType(), this).databaseTypeDefinition
           val name = add.fieldNames
-          updateClause += s"ALTER TABLE $tableName ADD COLUMN ${name(0)} $dataType"
+          updateClause += getAddColumnQuery(tableName, name(0), dataType)
         case rename: RenameColumn if rename.fieldNames.length == 1 =>
           val name = rename.fieldNames
           updateClause += s"ALTER TABLE $tableName RENAME COLUMN ${name(0)} TO ${rename.newName}"
@@ -223,17 +223,36 @@ abstract class JdbcDialect extends Serializable {
           val name = updateColumnType.fieldNames
           val dataType = JdbcUtils.getJdbcType(updateColumnType.newDataType(), this)
             .databaseTypeDefinition
-          updateClause += s"ALTER TABLE $tableName ALTER COLUMN ${name(0)} $dataType"
+          updateClause += getUpdateColumnTypeQuery(tableName, name(0), dataType)
         case updateNull: UpdateColumnNullability if updateNull.fieldNames.length == 1 =>
           val name = updateNull.fieldNames
           val nullable = if (updateNull.nullable()) "NULL" else "NOT NULL"
-          updateClause += s"ALTER TABLE $tableName ALTER COLUMN ${name(0)} SET $nullable"
+          updateClause += getUpdateColumnNullabilityQuery(tableName, name(0), updateNull.nullable())
         case _ =>
           throw new SQLFeatureNotSupportedException(s"Unsupported TableChange $change")
       }
     }
     updateClause.result()
   }
+
+  def getAddColumnQuery(tableName: String, columnName: String, dataType: String): String = {
+    s"ALTER TABLE $tableName ADD COLUMN $columnName $dataType"
+  }
+
+  def getUpdateColumnTypeQuery(
+      tableName: String,
+      columnName: String,
+      newDataType: String): String = {
+    s"ALTER TABLE $tableName ALTER COLUMN $columnName $newDataType"
+  }
+
+  def getUpdateColumnNullabilityQuery(
+      tableName: String,
+      columnName: String,
+      isNullable: Boolean): String = {
+    val nullable = if (isNullable) "NULL" else "NOT NULL"
+    s"ALTER TABLE $tableName ALTER COLUMN $columnName SET $nullable"
+  }
 }
 
 /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala
index 4c0623729e00d..cd9a2f5ea85ad 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala
@@ -112,4 +112,23 @@ private case object OracleDialect extends JdbcDialect {
       case _ => s"TRUNCATE TABLE $table"
     }
   }
+
+  // see https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_3001.htm#SQLRF01001
+  override def getAddColumnQuery(tableName: String, columnName: String, dataType: String): String =
+    s"ALTER TABLE $tableName ADD $columnName $dataType"
+
+  // see https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_3001.htm#SQLRF01001
+  override def getUpdateColumnTypeQuery(
+    tableName: String,
+    columnName: String,
+    newDataType: String): String =
+    s"ALTER TABLE $tableName MODIFY $columnName $newDataType"
+
+  override def getUpdateColumnNullabilityQuery(
+    tableName: String,
+    columnName: String,
+    isNullable: Boolean): String = {
+    val nullable = if (isNullable) "NULL" else "NOT NULL"
+    s"ALTER TABLE $tableName MODIFY $columnName $nullable"
+  }
 }