使用Mapper方式进行联表查询

有些业务场景需要查询两张表的数据，这时候就需要用到联表查询。下面将介绍两种方式进行联表查询。

场景：A模型页面，查询条件中包含B字段

模型A

@Model.model(YesOne.MODEL_MODEL)
@Model(displayName = "YesOne", summary = "YesOne")
public class YesOne extends IdModel {

    public static final String MODEL_MODEL = "top.YesOne";

    @Field.Integer
    @Field(displayName = "YesId")
    private Long yesId;

    @Field.String
    @Field(displayName = "名字")
    private String name;

    @Field.String
    @Field(displayName = "科目名字")
    private String professionalName;

    @Field(displayName = "关联YesTwo")
    @Field.many2one
    @Field.Relation(relationFields = {"yesId"},referenceFields = {"id"})
    private YesTwo yesTwo;

}

模型B

@Model.model(YesTwo.MODEL_MODEL)
@Model(displayName = "YesTwo", summary = "YesTwo")
public class YesTwo extends IdModel {

    public static final String MODEL_MODEL = "top.YesTwo";

    @Field.Integer
    @Field(displayName = "科目id")
    private Long professionalId;

    @Field.String
    @Field(displayName = "科目名字")
    private String professionalName;

}

1. 使用in的方式查询

通过B模型的查询条件查询出符合条件的所有数据ID，再根据这个ID去A模型里面查询出所需的数据。

    @Function.Advanced(displayName = "查询列表", type = FunctionTypeEnum.QUERY, category = FunctionCategoryEnum.QUERY_PAGE, managed = true)
    @Function(openLevel = {FunctionOpenEnum.LOCAL, FunctionOpenEnum.REMOTE, FunctionOpenEnum.API})
    public Pagination<YesOne> queryPage(Pagination<YesOne> page, IWrapper<YesOne> queryWrapper) {

        String professionalName = (String) queryWrapper.getQueryData().get("professionalName");
        if (StringUtils.isNotBlank(professionalName)) {
            List<Long> yesTwoId = new YesTwo().queryList(Pops.<YesTwo>lambdaQuery()
                            .from(YesTwo.MODEL_MODEL)
                            .eq(YesTwo::getProfessionalName, professionalName))
                    .stream().map(YesTwo::getId)
                    .collect(Collectors.toList());
            LambdaQueryWrapper<YesOne> wq = Pops.<YesOne>lambdaQuery().from(YesOne.MODEL_MODEL);
            if (CollectionUtils.isNotEmpty(yesTwoId)) {
                wq.in(YesOne::getYesId, yesTwoId);
            }
            return new YesOne().queryPage(page, wq);
        }
        return new YesOne().queryPage(page, queryWrapper);
    }

2. 使用mapper的方式查询

利用sql的方式去直接查询出结果。使用联表查询的方式查询

    @Autowired
    private YesOneQueryMapper yesOneQueryMapper;

    @Function.Advanced(displayName = "查询列表", type = FunctionTypeEnum.QUERY, category = FunctionCategoryEnum.QUERY_PAGE, managed = true)
    @Function(openLevel = {FunctionOpenEnum.LOCAL, FunctionOpenEnum.REMOTE, FunctionOpenEnum.API})
    public Pagination<YesOne> queryPage(Pagination<YesOne> page, IWrapper<YesOne> queryWrapper) {

        try (DsHintApi dsHint = DsHintApi.model(YesOne.MODEL_MODEL)) {
            String professionalName = (String) queryWrapper.getQueryData().get("professionalName");
            String yesOneTable = PamirsSession.getContext().getModelCache().get(YesOne.MODEL_MODEL).getTable();
            String yesTwoTable = PamirsSession.getContext().getModelCache().get(YesTwo.MODEL_MODEL).getTable();
            StringBuffer where = new StringBuffer().append("a.is_deleted = 0").append(CharacterConstants.SEPARATOR_BLANK)
                    .append(SqlConstants.AND).append(CharacterConstants.SEPARATOR_BLANK)
                    .append("b.is_deleted=0").append(CharacterConstants.SEPARATOR_BLANK);
            if (StringUtils.isNotBlank(professionalName)) {
                where.append(SqlConstants.AND).append(CharacterConstants.SEPARATOR_BLANK).append("b.").
                        append(PStringUtils.fieldName2Column(LambdaUtil.fetchFieldName(YesOne::getProfessionalName))).append(CharacterConstants.SEPARATOR_BLANK).
                        append(SqlConstants.EQ).append(professionalName);
            }
            StringBuffer limit = new StringBuffer().append(page.getStart() + " , " + page.getSize());
            List<YesOne> yesOnes = yesOneQueryMapper.unionTableQuery(yesOneTable, yesTwoTable, where.toString(), limit.toString());
            Long total = yesOneQueryMapper.queryTotal(yesOneTable, yesTwoTable, where.toString());
            page.setTotalElements(total);
            page.setContent(yesOnes);
        }
        return page;
    }

接口

package pro.shushi.pamirs.top.core.service;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import pro.shushi.pamirs.top.api.model.YesOne;

import java.util.List;

@Mapper
public interface YesOneQueryMapper {

    @Select("<script>"
            + "SELECT "
            + "a.id , "
            + "a.name, "
            + "b.professional_name as professionalName "
            + "FROM ${yesOne} a "
            + "INNER JOIN ${yesTwo} b ON a.yes_id = b.id "
            + "<if test='whereConditions != null'>"
            + "where (${whereConditions}) "
            + "</if>"
            + "ORDER BY a.id ASC "
            + "<if test='limitConditions != null'>"
            + "LIMIT ${limitConditions} "
            + "</if>"
            + "</script>")
    List<YesOne> unionTableQuery(@Param("yesOne") String yesOne, @Param("yesTwo") String yesTwo, @Param("whereConditions") String whereConditions, @Param("limitConditions") String limitConditions);

    @Select("<script>"
            + "SELECT count(a.id )"
            + "FROM ${yesOne} a "
            + "INNER JOIN ${yesTwo} b ON a.yes_id = b.id "
            + "<if test='whereConditions != null'>"
            + "where (${whereConditions}) "
            + "</if>"
            + "</script>")
    Long queryTotal(@Param("yesOne") String yesOne, @Param("yesTwo") String yesTwo, @Param("whereConditions") String whereConditions);

}