mybatis之updateByPrimaryKey、updateByPrimaryKeySelective、updateByExampleSelective

方法：updateByPrimaryKey 更新对象的字段为null也会被更新，数据库数据被覆盖

SBox record1 = new SBox();

record1.setStreamBoxId(sBoxes.get(0).getStreamBoxId());

System.out.println(record1.getStreamBoxId());

record1.setCapability(3001d);

record1.setUseState((byte)1);

record1.setOpState((byte)1);

streamBoxDao.updateByPrimaryKey(record1);

sql解析：

==> Preparing: UPDATE stream_box SET stream_line_id = ?,start_time = ?,end_time =

?,capability = ?,use_state = ?,op_state = ?,set_id = ?,req_id = ?,spec_id = ?,pre_set_id

= ?,pre_use_capability = ?,last_set_id = ?,last_use_capability = ? WHERE stream_box_id =

?

==> Parameters: null, null, null, 3001.0(Double), 1(Byte), 1(Byte), null, null, null,

null, null, null, null, sboxinsertTKMybatis1(String)

结论：更新的对象中，没有给值的字段也会被更新到数据库中。

方法：updateByPrimaryKeySelective 只会更新对象中有值字段

SBox record2 = new SBox();

record2.setStreamBoxId(sBoxes.get(1).getStreamBoxId());

record2.setCapability(3002d);

record2.setUseState((byte)1);

record2.setOpState((byte)1);

System.out.println(record2.getStreamBoxId());

streamBoxDao.updateByPrimaryKeySelective(record2);

sql解析：

==> Preparing: UPDATE stream_box SET capability = ?,use_state = ?,op_state = ? WHERE stream_box_id = ?

==> Parameters: 3002.0(Double), 1(Byte), 1(Byte), sboxinsertTKMybatis2(String)

<== Updates: 1

结论：更新的对象中，没有给值的字段不会被更新到数据库中，只会更新对象中有值字段

方法：updateByExampleSelective 只会更新满足条件的数据中对象中有字段的值

SBox record3 = new SBox();

record3.setStreamBoxId(sBoxes.get(3).getStreamBoxId());

record3.setCapability(3004d);

record3.setUseState((byte)1);

record3.setOpState((byte)1);

System.out.println(record3.getStreamBoxId());

Example example = new Example(SBox.class);

Example.Criteria criteria = example.createCriteria();

criteria.andEqualTo("streamBoxId",record3.getStreamBoxId());

streamBoxDao.updateByExampleSelective(record3,example);

sql解析

==> Preparing: UPDATE stream_box SET capability = ?,use_state = ?,op_state = ? WHERE ( ( stream_box_id = ? ) )

==> Parameters: 3004.0(Double), 1(Byte), 1(Byte), sboxinsertTKMybatis4(String)

<== Updates: 1

结论：按条件更新成对象中有字段的值，没有给值的字段不会被更新到数据库中，只会更新对象中有值字段

方法：updateByExample 更新满足条件的数据中对象所有值，包括null

SBox record3 = new SBox();

record3.setStreamBoxId(sBoxes.get(3).getStreamBoxId());

record3.setCapability(3005d);

record3.setUseState((byte)1);

record3.setOpState((byte)1);

System.out.println(record3.getStreamBoxId());

Example example = new Example(SBox.class);

Example.Criteria criteria = example.createCriteria();

criteria.andEqualTo("streamBoxId",record3.getStreamBoxId());

//streamBoxDao.updateByExampleSelective(record3,example);

streamBoxDao.updateByExample(record3,example);

sql解析

==> Preparing: UPDATE stream_box SET stream_line_id = ?,start_time = ?,end_time = ?,capability = ?,use_state = ?,op_state = ?,set_id = ?,req_id = ?,spec_id = ?,pre_set_id = ?,pre_use_capability = ?,last_set_id = ?,last_use_capability = ? WHERE ( ( stream_box_id = ? ) )

==> Parameters: null, null, null, 3005.0(Double), 1(Byte), 1(Byte), null, null, null, null, null, null, null, sboxinsertTKMybatis4(String)

<== Updates: 1

结论：按条件更新，满足条件的数据库表数据，都会更新成对象的值，没有给值的字段也会被更新到数据库中。