code: public static String getKeyInWhereSQL(Class<?> clazz) {
  		Field keyField = DOInfoReader.getOneKeyColumn(clazz);
  		return autoSetSoftDeleted("WHERE " +
  	           getColumnName(keyField.getAnnotation(Column.class)) + " in (?)", clazz);
  	}
docs: 获得主键in(?)的where子句，包含where关键字。会自动处理软删除条件
  @param clazz
  @return