在使用MyBatis-Plus的MPJLambdaWrapper进行连表查询时,如果需要对查询结果进行去重,可以通过SQL的DISTINCT关键字来实现。下面我将分点详细解释如何实现MPJLambdaWrapper连表查询去重,并提供相应的代码示例。 1. 理解MPJLambdaWrapper的功能和用法 MPJLambdaWrapper是MyBatis-Plus提供的一个查询构造器,它允许开发者通过链式调...
private Map<String, Double> queryWeight() { QueryWrapper<TagWeight> wrapper = new QueryWrapper<>(); wrapper.lambda().likeRight(TagWeight::getTagType, "101109"); List<TagWeight> list = tagWeightService.list(wrapper); if (CollectionUtils.isEmpty(list)) { return Maps.newHashMap(); return li...
实现的java代码参考如下通过分组来查询分页的使用代码 @DataSource(DataSourceType.HW_BUSINESS) public IPageselectDistinctDsByPage(DsQueryForm queryForm) { Integer currentPage = queryForm.getCurrentPage(); Integer pageSize = queryForm.getPageSize(); Pagepage = new Page<>(currentPage, pageSize); La...
.select(User::getName,User::getAge) .list(); AI代码助手复制代码 2.6 查询去重 如果我们需要对查询结果进行去重,可以使用distinct()方法。例如,查询所有不重复的年龄: List<Integer>ageList=userService.lambdaQuery() .select(User::getAge) .distinct() .list(); AI代码助手复制代码 3. lambdaUpdate() ...
public IPage<Ds> selectDistinctDsByPage(DsQueryForm queryForm) { Integer currentPage = queryForm.getCurrentPage(); Integer pageSize = queryForm.getPageSize(); Page<Ds> page = new Page<>(currentPage, pageSize); LambdaQueryWrapper<Ds> lqw = new LambdaQueryWrapper<>(); ...
LambdaQueryWrapper<Dict> wrapper = Wrappers.lambdaQuery(); wrapper.eq(Dict::getDictCode, dictCode.getCode()) .eq(Dict::getEnabled, DictEnableEnum.VALID.getType()); return this.baseMapper.selectList(wrapper); } 1. 2. 3. 4. 5. 6. ...
public IPage<Ds> selectDistinctDsByPage(DsQueryForm queryForm) { Integer currentPage = queryForm.getCurrentPage(); Integer pageSize = queryForm.getPageSize(); Page<Ds> page = new Page<>(currentPage, pageSize); LambdaQueryWrapper<Ds> lqw = new LambdaQueryWrapper<>(); ...
`Wrappers.<Order>query().select("distinct order_code")` 这种在代码里硬编码数据库字段名,给人感觉非常的不规范,那是否可以像lambdaQuery那样,不硬编码也可以获取到数据库字段名呢?类似这样子: String columName = columnResolver.getColumn(Order::getOrderCode); ...
getSql(), sqlFirst(), sqlDistinct(), sqlSelectColumns(tableInfo, true), 32 + mpjTableName(tableInfo), sqlAlias(), sqlFrom(), sqlWhereEntityWrapper(true, tableInfo), mpjSqlOrderBy(tableInfo), sqlComment()); 33 + SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, ...
public static final int DISTINCT = 0x00000001; * Characteristic value signifying that encounter order follows a defined * sort order. If so, method {@link #getComparator()} returns the associated * Comparator, or {@code null} if all elements are {@link Comparable} and ...