Using Easy-Query ORM for Strongly Typed OLTP and OLAP Queries in Java

Easy-Query is a Java ORM that provides strong‑typed OLTP and OLAP query capabilities, allowing developers to write type‑safe queries without writing raw SQL.

It supports many‑to‑many and one‑to‑one relationships, automatic joins, and can generate SQL for complex queries such as filtering users by city, selecting specific fields, counting related entities, and applying aggregate functions.

Entity definitions (excerpt):

@Table("t_user")

@Data

@EntityProxy

public class SysUser implements ProxyEntityAvailable<SysUser, SysUserProxy> {

@Column(primaryKey = true)

private String id;

private String name;

private LocalDateTime createTime;

@Navigate(value = RelationTypeEnum.ManyToMany, mappingClass = UserRole.class, selfMappingProperty = "userId", targetMappingProperty = "roleId")

private List<SysRole> roles;

@Navigate(value = RelationTypeEnum.OneToOne, targetProperty = "userId")

private SysUserAddress address;

@Override

public Class<SysUserProxy> proxyTableClass() {

return SysUserProxy.class;

}

}

@Table("t_role")

@Data

@EntityProxy

public class SysRole implements ProxyEntityAvailable<SysRole, SysRoleProxy> {

@Column(primaryKey = true)

private String id;

private String name;

private LocalDateTime createTime;

@Navigate(value = RelationTypeEnum.ManyToMany, mappingClass = UserRole.class, selfMappingProperty = "roleId", targetMappingProperty = "userId")

private List<SysUser> users;

@Navigate(value = RelationTypeEnum.ManyToMany, mappingClass = RoleMenu.class, selfMappingProperty = "roleId", targetMappingProperty = "menuId")

private List<SysMenu> menus;

@Override

public Class<SysRoleProxy> proxyTableClass() {

return SysRoleProxy.class;

}

}

Query examples:

Query users in Hangzhou or Shaoxing:

List<SysUser> userInHz = easyEntityQuery.queryable(SysUser.class)

.where(s -> {

s.or(() -> {

s.address().city().eq("杭州市");

s.address().city().eq("绍兴市");

});

}).toList();

Corresponding SQL:

SELECT `id`, `name`, `create_time` FROM `t_user` t

LEFT JOIN `t_user_address` t1 ON t1.`user_id` = t.`id`

WHERE (t1.`city` = '杭州市' OR t1.`city` = '绍兴市');

Query a user named "小明" and return his name and address:

List<Draft2<String, String>> userNameAndAddr = easyEntityQuery.queryable(SysUser.class)

.where(s -> s.name().eq("小明"))

.select(s -> Select.DRAFT.of(s.name(), s.address().addr()))

.toList();

Query a user named "小明" and also return the count of his roles:

List<Draft3<String, String, Long>> userNameAndAddrAndRoleCount = easyEntityQuery.queryable(SysUser.class)

.where(s -> s.name().eq("小明"))

.select(s -> Select.DRAFT.of(s.name(), s.address().addr(), s.roles().count()))

.toList();

Other cases demonstrate filtering by role name, counting roles, using aggregate functions like MAX, and pagination of related collections.

DTO generation with EasyQueryAssistant:

The IDE plugin can generate structured DTO classes that map the entity hierarchy automatically.

@Data

public class UserRoleMenuDTO {

private String id;

private String name;

@Navigate(value = RelationTypeEnum.ManyToMany)

private List<InternalRoles> roles;

public static class InternalRoles {

private String id;

private String name;

@Navigate(value = RelationTypeEnum.ManyToMany)

private List<InternalMenus> menus;

}

public static class InternalMenus {

private String id;

private String name;

private String route;

private String icon;

}

}

Using selectAutoInclude the generated DTO can be populated directly:

List<UserRoleMenuDTO> result = easyEntityQuery.queryable(SysUser.class)

.where(u -> {

u.name().like("小明");

u.createTime().rangeClosed(LocalDateTime.now().minusDays(100), LocalDateTime.now());

})

.selectAutoInclude(UserRoleMenuDTO.class)

.toList();

Overall, Easy-Query demonstrates a powerful, zero‑dependency, fully open‑source solution for both OLTP and OLAP scenarios in Java, supporting complex joins, aggregates, and automatic DTO mapping.

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