1、动态SQL操作之查询
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查询条件不确定，需要根据情况产生SQL语法，这种情况叫动态SQL
select emp_id,emp_name,emp_sal from emp
and emp_id = #{pid}
and emp_name like #{pname}
and emp_sal < #{psal}
2、动态SQL操作之更新
更新条件不确定，需要根据情况产生SQL语法，这种情况叫动态SQL
update emp
emp_name = #{pname},
emp_sal = #{psal},
where emp_id = #{pid}
3、动态SQL操作之删除
根据多个id进行删除
delete from emp where emp_id in
#{pid}
delete from emp where emp_id in
#{pid}
4、动态SQL操作之添加
根据条件，添加数据
emp_id,
emp_name,
emp_sal,
#{id},
#{name},
#{sal},
insert into emp() values()
5、参考代码
准备SQL
CREATE TABLE Emp(
emp_id INT(5) PRIMARY KEY,
emp_name VARCHAR(20),
emp_sal DOUBLE(8,2)
);
Emp.java
package com.rk.entity;
public class Emp {
private Integer id;
private String name;
private Double sal;
public Emp(){}
public Emp(Integer id, String name, Double sal) {
this.id = id;
this.name = name;
this.sal = sal;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSal() {
return sal;
}
public void setSal(Double sal) {
this.sal = sal;
}
}EmpMapper.xml
select emp_id,emp_name,emp_sal from emp
and emp_id = #{pid}
and emp_name like #{pname}
and emp_sal < #{psal}
update emp
emp_name = #{pname},
emp_sal = #{psal},
where emp_id = #{pid}
delete from emp where emp_id in
#{pid}
delete from emp where emp_id in
#{pid}
emp_id,
emp_name,
emp_sal,
#{id},
#{name},
#{sal},
insert into emp() values()
mybatis.xml
db.properties
mysql.driver=com.mysql.jdbc.Driver
mysql.url=jdbc:mysql://127.0.0.1:3306/testdb
mysql.username=root
mysql.password=root
oracle.driver=oracle.jdbc.driver.OracleDriver
oracle.url=jdbc:oracle:thin:@127.0.0.1:1521:orcl
oracle.username=scott
oracle.password=tiger
MyBatisUtils.java
package com.rk.utils;
import java.io.IOException;
import java.io.Reader;
import java.sql.Connection;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MyBatisUtils {
private static ThreadLocal threadLocal = new ThreadLocal();
private static SqlSessionFactory sqlSessionFactory;
static{
try {
Reader reader = Resources.getResourceAsReader("mybatis.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private MyBatisUtils() {}
public static SqlSession getSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession == null){
sqlSession = sqlSessionFactory.openSession();
threadLocal.set(sqlSession);
}
return sqlSession;
}
public static void closeSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession != null){
sqlSession.close();
threadLocal.remove();
}
}
public static void main(String[] args) {
Connection conn = MyBatisUtils.getSqlSession().getConnection();
System.out.println(conn!=null ? "连接成功" : "连接失败");
}
}EmpDao.java
package com.rk.dao;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import com.rk.entity.Emp;
import com.rk.utils.MyBatisUtils;
public class EmpDao {
/**
* 动态SQL之SELECT
*/
public List dynamicFind(Integer id,String name,Double sal){
SqlSession sqlSession = null;
try {
Map map = new HashMap();
map.put("pid", id);
map.put("pname", name != null ? "%"+name+"%" : null);
map.put("psal", sal);
sqlSession = MyBatisUtils.getSqlSession();
return sqlSession.selectList(Emp.class.getName() + ".dynamicFind", map);
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return null;
}
@Test
public void testDynamicFind(){
EmpDao dao = new EmpDao();
//List list = dao.dynamicFind(1,null, null);
//List list = dao.dynamicFind(null,"tom", null);
//List list = dao.dynamicFind(null,null, 350D);
List list = dao.dynamicFind(null,"tom", 350D);
// List list = dao.dynamicFind(0,"tom", 25D);
if(list != null && list.size()>0){
for(Emp emp : list){
System.out.println( emp.getName() + ":"+emp.getSal());
}
}
}
/**
* 动态SQL之UPDATE
*/
public int dynamicUpdate(Integer id,String name,Double sal){
SqlSession sqlSession = null;
try {
Map map = new HashMap();
map.put("pid", id);
map.put("pname", name);
map.put("psal", sal);
sqlSession = MyBatisUtils.getSqlSession();
int i=sqlSession.update(Emp.class.getName() + ".dynamicUpdate", map);
sqlSession.commit();
return i;
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return 0;
}
@Test
public void testDynamicUpdate(){
int i = dynamicUpdate(3,"Lucy",null);
System.out.println("本次操作影响"+i+"行数据");
}
/**
* 动态SQL之DELETE（数组版本）
*/
public int dynamicDeleteArray(int... ids){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i=sqlSession.update(Emp.class.getName() + ".dynamicDeleteArray", ids);
sqlSession.commit();
return i;
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return 0;
}
@Test
public void testDynamicDeleteArray(){
int i = dynamicDeleteArray(3,2);
System.out.println("本次操作影响"+i+"行数据");
}
/**
* 动态SQL之DELETE（集合版本）
*/
public int dynamicDeleteList(List ids){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i=sqlSession.update(Emp.class.getName() + ".dynamicDeleteList", ids);
sqlSession.commit();
return i;
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return 0;
}
@Test
public void testDynamicDeleteList(){
List ids = new ArrayList();
ids.add(1);
ids.add(4);
int i = dynamicDeleteList(ids);
System.out.println("本次操作影响"+i+"行数据");
}
/**
* 动态SQL之INSERT
*/
public int dynamicInsert(Emp emp){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i=sqlSession.insert(Emp.class.getName() + ".dynamicInsert", emp);
sqlSession.commit();
return i;
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
return 0;
}
@Test
public void testDynamicInsert(){
Emp emp = new Emp(1, null, 30D);
int i = dynamicInsert(emp);
System.out.println("本次操作影响"+i+"行数据");
}
}
网站题目：MyBatis系列：（5）动态SQL
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