boolean ifExists = readIfExists(false);
AlterTableAlterColumn command = new AlterTableAlterColumn(session, table.getSchema());
command.setType(CommandInterface.ALTER_TABLE_DROP_COLUMN);
String columnName = readColumnIdentifier();
command.setTable(table);
if (ifExists && !table.doesColumnExist(columnName)) {
return new NoOperation(session);
}
command.setOldColumn(table.getColumn(columnName));
return command;
}