### Question:
JdbcDBClient extends DB { @Override public Status delete(String tableName, String key) { try { StatementType type = new StatementType(StatementType.Type.DELETE, tableName, 1, "", getShardIndexByKey(key)); PreparedStatement deleteStatement = cachedStatements.get(type); if (deleteStatement == null) { deleteStatement = createAndCacheDeleteStatement(type, key); } deleteStatement.setString(1, key); int result = deleteStatement.executeUpdate(); if (result == 1) { return Status.OK; } return Status.UNEXPECTED_STATE; } catch (SQLException e) { System.err.println("Error in processing delete to table: " + tableName + e); return Status.ERROR; } }  @Override void init(); @Override void cleanup(); @Override Status read(String tableName, String key, Set<String> fields, HashMap<String, ByteIterator> result); @Override Status scan(String tableName, String startKey, int recordcount, Set<String> fields,
                     Vector<HashMap<String, ByteIterator>> result); @Override Status update(String tableName, String key, HashMap<String, ByteIterator> values); @Override Status insert(String tableName, String key, HashMap<String, ByteIterator> values); @Override Status delete(String tableName, String key); static final String DRIVER_CLASS; static final String CONNECTION_URL; static final String CONNECTION_USER; static final String CONNECTION_PASSWD; static final String DB_BATCH_SIZE; static final String JDBC_FETCH_SIZE; static final String JDBC_AUTO_COMMIT; static final String FIELD_COUNT_PROPERTY; static final String FIELD_COUNT_PROPERTY_DEFAULT; static final String NULL_VALUE; static final String PRIMARY_KEY; static final String COLUMN_PREFIX; }### Answer:
@Test public void deleteTest() { try { insertRow("user0"); String deleteKey = "user1"; insertRow(deleteKey); insertRow("user2"); jdbcDBClient.delete(TABLE_NAME, deleteKey); ResultSet resultSet = jdbcConnection.prepareStatement( String.format("SELECT * FROM %s", TABLE_NAME) ).executeQuery(); int totalRows = 0; while (resultSet.next()) { assertNotEquals("Assert this is not the deleted row key", deleteKey, resultSet.getString(KEY_FIELD)); totalRows++; } assertEquals("Assert we ended with the correct number of rows", totalRows, 2); resultSet.close(); } catch (SQLException e) { e.printStackTrace(); fail("Failed deleteTest"); } }