数据库连接方式
package cn.itcast.a_hql; import java.util.Arrays; import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.Transaction; import org.junit.Test; import cn.itcast.domain.Customer; import cn.itcast.utils.HibernateUtils; //学习HQL语法(不常用) - 多表查询语法 public class Demo2 { //回顾-原生SQL // 交叉连接-笛卡尔积(避免) // select * from A,B // 内连接 // |-隐式内连接 // select * from A,B where b.aid = a.id // |-显式内连接 // select * from A inner join B on b.aid = a.id // 外连接 // |- 左外 // select * from A left [outer] join B on b.aid = a.id // |- 右外 // select * from A right [outer] join B on b.aid = a.id //--------------------------------------------------------------------- //HQL的多表查询 //内连接(迫切) //外连接 // |-左外(迫切) // |-右外(迫切) @Test //HQL 内连接 => 将连接的两端对象分别返回.放到数组中. public void fun1(){ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //---------------------------------------------------- String hql = " from Customer c inner join c.linkMens "; Query query = session.createQuery(hql); List<Object[]> list = query.list(); for(Object[] arr : list){ System.out.println(Arrays.toString(arr)); } //---------------------------------------------------- tx.commit(); session.close(); } @Test //HQL 迫切内连接 => 帮我们进行封装.返回值就是一个对象 public void fun2(){ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //---------------------------------------------------- String hql = " from Customer c inner join fetch c.linkMens "; Query query = session.createQuery(hql); List<Customer> list = query.list(); System.out.println(list); //---------------------------------------------------- tx.commit(); session.close(); } @Test //HQL 左外连接 => 将连接的两端对象分别返回.放到数组中. public void fun3(){ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //---------------------------------------------------- String hql = " from Customer c left join c.linkMens "; Query query = session.createQuery(hql); List<Object[]> list = query.list(); for(Object[] arr : list){ System.out.println(Arrays.toString(arr)); } //---------------------------------------------------- tx.commit(); session.close(); } @Test //HQL 右外连接 => 将连接的两端对象分别返回.放到数组中. public void fun4(){ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //---------------------------------------------------- String hql = " from Customer c right join c.linkMens "; Query query = session.createQuery(hql); List<Object[]> list = query.list(); for(Object[] arr : list){ System.out.println(Arrays.toString(arr)); } //---------------------------------------------------- tx.commit(); session.close(); } }
package cn.itheima.domain; public class Customer { /* * CREATE TABLE `cst_customer` ( `cust_id` BIGINT(32) NOT NULL AUTO_INCREMENT COMMENT '客户编号(主键)', `cust_name` VARCHAR(32) NOT NULL COMMENT '客户名称(公司名称)', `cust_source` VARCHAR(32) DEFAULT NULL COMMENT '客户信息来源', `cust_industry` VARCHAR(32) DEFAULT NULL COMMENT '客户所属行业', `cust_level` VARCHAR(32) DEFAULT NULL COMMENT '客户级别', `cust_linkman` VARCHAR(64) DEFAULT NULL COMMENT '联系人', `cust_phone` VARCHAR(64) DEFAULT NULL COMMENT '固定电话', `cust_mobile` VARCHAR(16) DEFAULT NULL COMMENT '移动电话', PRIMARY KEY (`cust_id`) ) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8; */ private Long cust_id; private String cust_name; private String cust_source; private String cust_industry; private String cust_level; private String cust_linkman; private String cust_phone; private String cust_mobile; public Long getCust_id() { return cust_id; } public void setCust_id(Long cust_id) { this.cust_id = cust_id; } public String getCust_name() { return cust_name; } public void setCust_name(String cust_name) { this.cust_name = cust_name; } public String getCust_source() { return cust_source; } public void setCust_source(String cust_source) { this.cust_source = cust_source; } public String getCust_industry() { return cust_industry; } public void setCust_industry(String cust_industry) { this.cust_industry = cust_industry; } public String getCust_level() { return cust_level; } public void setCust_level(String cust_level) { this.cust_level = cust_level; } public String getCust_linkman() { return cust_linkman; } public void setCust_linkman(String cust_linkman) { this.cust_linkman = cust_linkman; } public String getCust_phone() { return cust_phone; } public void setCust_phone(String cust_phone) { this.cust_phone = cust_phone; } public String getCust_mobile() { return cust_mobile; } public void setCust_mobile(String cust_mobile) { this.cust_mobile = cust_mobile; } @Override public String toString() { return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + "]"; } }
package cn.itheima.domain; //联系人实体 public class LinkMan { /* * CREATE TABLE `cst_linkman` ( `lkm_id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '联系人编号(主键)', `lkm_name` varchar(16) DEFAULT NULL COMMENT '联系人姓名', `lkm_cust_id` bigint(32) NOT NULL COMMENT '客户id', `lkm_gender` char(1) DEFAULT NULL COMMENT '联系人性别', `lkm_phone` varchar(16) DEFAULT NULL COMMENT '联系人办公电话', `lkm_mobile` varchar(16) DEFAULT NULL COMMENT '联系人手机', `lkm_email` varchar(64) DEFAULT NULL COMMENT '联系人邮箱', `lkm_qq` varchar(16) DEFAULT NULL COMMENT '联系人qq', `lkm_position` varchar(16) DEFAULT NULL COMMENT '联系人职位', `lkm_memo` varchar(512) DEFAULT NULL COMMENT '联系人备注', PRIMARY KEY (`lkm_id`), KEY `FK_cst_linkman_lkm_cust_id` (`lkm_cust_id`), CONSTRAINT `FK_cst_linkman_lkm_cust_id` FOREIGN KEY (`lkm_cust_id`) REFERENCES `cst_customer` (`cust_id`) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8; */ private Long lkm_id; private Character lkm_gender; private String lkm_name; private String lkm_phone; private String lkm_email; private String lkm_qq; private String lkm_mobile; private String lkm_memo; private String lkm_position; //表达多对一关系 private Customer customer ; //---------------------------------------------- //不与数据库中的列对应,只为了接收表单参数 private Long cust_id; public Long getCust_id() { return cust_id; } public void setCust_id(Long cust_id) { this.cust_id = cust_id; } public Customer getCustomer() { return customer; } public void setCustomer(Customer customer) { this.customer = customer; } public Long getLkm_id() { return lkm_id; } public void setLkm_id(Long lkm_id) { this.lkm_id = lkm_id; } public Character getLkm_gender() { return lkm_gender; } public void setLkm_gender(Character lkm_gender) { this.lkm_gender = lkm_gender; } public String getLkm_name() { return lkm_name; } public void setLkm_name(String lkm_name) { this.lkm_name = lkm_name; } public String getLkm_phone() { return lkm_phone; } public void setLkm_phone(String lkm_phone) { this.lkm_phone = lkm_phone; } public String getLkm_email() { return lkm_email; } public void setLkm_email(String lkm_email) { this.lkm_email = lkm_email; } public String getLkm_qq() { return lkm_qq; } public void setLkm_qq(String lkm_qq) { this.lkm_qq = lkm_qq; } public String getLkm_mobile() { return lkm_mobile; } public void setLkm_mobile(String lkm_mobile) { this.lkm_mobile = lkm_mobile; } public String getLkm_memo() { return lkm_memo; } public void setLkm_memo(String lkm_memo) { this.lkm_memo = lkm_memo; } public String getLkm_position() { return lkm_position; } public void setLkm_position(String lkm_position) { this.lkm_position = lkm_position; } }
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping SYSTEM "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd" PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"> <!-- 配置表与实体对象的关系 --> <!-- package属性:填写一个包名.在元素内部凡是需要书写完整类名的属性,可以直接写简答类名了. --> -<hibernate-mapping package="cn.itheima.domain"> <!-- class元素: 配置实体与表的对应关系的 name: 完整类名 table:数据库表名 --> -<class table="cst_customer" name="Customer"> <!-- id元素:配置主键映射的属性 name: 填写主键对应属性名 column(可选): 填写表中的主键列名.默认值:列名会默认使用属性名 type(可选):填写列(属性)的类型.hibernate会自动检测实体的属性类型. 每个类型有三种填法: java类型|hibernate类型|数据库类型 not-null(可选):配置该属性(列)是否不能为空. 默认值:false length(可选):配置数据库中列的长度. 默认值:使用数据库类型的最大长度 --> -<id name="cust_id"> <!-- generator:主键生成策略(明天讲) --> <generator class="native"/> </id> <!-- property元素:除id之外的普通属性映射 name: 填写属性名 column(可选): 填写列名 type(可选):填写列(属性)的类型.hibernate会自动检测实体的属性类型. 每个类型有三种填法: java类型|hibernate类型|数据库类型 not-null(可选):配置该属性(列)是否不能为空. 默认值:false length(可选):配置数据库中列的长度. 默认值:使用数据库类型的最大长度 --> -<property name="cust_name" column="cust_name"> <!-- <column name="cust_name" sql-type="varchar" ></column> --> </property> <property name="cust_source" column="cust_source"/> <property name="cust_industry" column="cust_industry"/> <property name="cust_level" column="cust_level"/> <property name="cust_linkman" column="cust_linkman"/> <property name="cust_phone" column="cust_phone"/> <property name="cust_mobile" column="cust_mobile"/> </class> </hibernate-mapping>
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping SYSTEM "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd" PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"> -<hibernate-mapping package="cn.itheima.domain"> -<class table="cst_linkman" name="LinkMan"> -<id name="lkm_id"> <generator class="native"/> </id> <property name="lkm_gender"/> <property name="lkm_name"/> <property name="lkm_phone"/> <property name="lkm_email"/> <property name="lkm_qq"/> <property name="lkm_mobile"/> <property name="lkm_memo"/> <property name="lkm_position"/> <!-- 多对一 --> <!-- name属性:引用属性名 column属性: 外键列名 class属性: 与我关联的对象完整类名 --> <!-- 级联操作: cascade save-update: 级联保存更新 delete:级联删除 all:save-update+delete 级联操作: 简化操作.目的就是为了少些两行代码. --> <!-- 多的一方: 不能放弃维护关系的.外键字段就在多的一方. --> <many-to-one name="customer" class="Customer" column="lkm_cust_id"> </many-to-one> </class> </hibernate-mapping>