博客

一、查询

1、获取oracle序列

<select id="getId" resultType="int">
    select user_seq.nextval from dual
</select>

2、查询多条记录

<select id="getUsers" parameterType="string" resultType="map">
    select * from user where username=#{username}
</select>

dao接口处：public List<Map<String,Object>> getUsers(String username);

二、增加

<insert id="addUser" parameterType="com.tjx.entity.User">
    insert into User(id,username) values(#{id},#{username})
</insert>

三、删除

<delete id="deleteUser" parameterType="string">
    delete from User where id=#{id}
   </delete>

dao接口处：public int deleteUser(String id);

四、更新

<update id="updateUser" parameterType="com.tjx.entity.User">
    update User set username=#{username} where id=#{id}
</update >

五、if test

<select id="getUsers" parameterType="string" resultType="map">
    select * from user where 1=1 
<if test="username!=null and username!=''">
	and username=#{username}
</select>

六、模糊查询%$%

<select id="getUsers" parameterType="string" resultType="map">
    select * from user where 1=1
	<if test="username!= null and username!='' ">
		and username  like  '%${username}%'
	</if>
</select>

七、<>的应用

where  rn <![CDATA[ > ]]> ((${page}-1) * ${rows}) and rn <![CDATA[ <= ]]> (${page} * ${rows})