主要是设计到映射文件的编写:

SELECT:

<sql id="query_user_where">
<!-- test里面可以编写OGNL表达式 -->
<!-- 判断字符串不为空的标准写法 -->
<if test=" user.username != null and user.username !='' ">
AND username like '%${user.username}%'
</if>
</sql> <!-- 分页查询之查询记录 -->
<select id="findUserList" parameterType="UserQueryVO"
resultType="user">
SELECT * FROM user
<where>
<include refid="query_user_where" />
</where>
</select>

if语句前面必须带AND,where会自己判断什么时候该去除

UPDATE:

<update id="testDSQL" parameterType="User">
UPDATE user
<set>
<if test="username != null and username != ''">
username = #{username},
</if>
<if test="address != null and address != ''">
address = #{address},
</if>
</set>
WERE id = 36
</update>

if最后的逗号是必须写的,set会自己判断什么时候去除

INSERT:

<insert id="insertSelective" parameterType="com.kkb.mybatis.pojo.Account" >
<selectKey resultType="java.lang.Integer" keyProperty="id" order="AFTER" >
SELECT LAST_INSERT_ID()
</selectKey>
INSERT INTO account
<trim prefix="(" suffix=")" suffixOverrides="," >
<if test="name != null" >
name,
</if>
<if test="money != null" >
money,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides="," >
<if test="name != null" >
#{name,jdbcType=VARCHAR},
</if>
<if test="money != null" >
#{money,jdbcType=DOUBLE},
</if>
</trim>
</insert>

if最后的逗号是必须写的,trim会自己判断什么时候去除

05-07 15:57
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