SSM 框架学习 (MyBatis篇)
二、MyBatis 动态SQL使用
在上一个项目的基础上修改，这里主要展示修改部分的内容
1、用户表查询操作-if
<!-- 查询用户列表 动态条件查询-if
如果不使用if，当roleName为空或userName为空时会出现sql异常
查看日志可看到异常：select * from db where and userName=?
-->
<select id="getUserList" resultMap="userList">
select u.*, r.roleName from smbms_user u, smbms_role r
where u.userRole = r.id
<if test="userRole != null">
and u.userRole = #{userRole}
</if>
<if test="userName != null and userName != ''">
and u.userName like CONCAT ('%',#{userName},'%')
</if>
</select>2、 动态条件查询-if-where
<!-- 查询用户列表 动态条件查询-if-where-->
<select id="getUserList" resultMap="userList">
select u.*, r.roleName from smbms_user u, smbms_role r
<where>
u.userRole = r.id
<if test="userName != null and userName != ''" >
and u.userName like CONCAT ('%',#{userName},'%')
</if>
<if test="userRole != null">
and r.userRole = #{userRole}
</if>
</where>
</select>3、 动态条件更新数据-if-set
<!-- 修改用户信息-if-set -->
<update id="modify" parameterType="User">
update smbms_user
<set>
<if test="userCode != null">userCode=#{userCode},</if>
<if test="userName != null">userName=#{userName},</if>
<if test="userPassword != null">userPassword=#{userPassword},</if>
<if test="gender != null">gender=#{gender},</if>
<if test="birthday != null">birthday=#{birthday},</if>
<if test="phone != null">phone=#{phone},</if>
<if test="address != null">address=#{address},</if>
<if test="userRole != null">userRole=#{userRole},</if>
<if test="modifyBy != null">modifyBy=#{modifyBy},</if>
<if test="modifyDate != null">modifyDate=#{modifyDate}</if>
</set>
where id=#{id}
</update>4、 动态条件查找数据-if-trim-prefix-prefixOverrides
<!-- 查询用户列表 动态条件查询-if-trim-prefix-prefixOverrides -->
<select id="getUserList" resultMap="userList">
select * from smbms_user
<trim prefix="where" prefixOverrides="and|or">
<!--
如果满足条件，下面的语句会连接到上面的语句，trim会将第一个连上来的语句的and或or替换成where
prefix:前缀 prefixOverrides：被替换的词，用 ’|‘分隔，不能有空格（我的测试是这样）
-->
<if test="userName != null and userName != ''">
and userName like CONCAT ('%',#{userName},'%')
</if>
<if test="userRole != null">
and userRole = #{userRole}
</if>
</trim>
</select>5、 动态条件修改数据-if-trim-prefix-suffixOverrides-suffix
<!-- 修改用户信息-if-trim-suffix-suffixOverrides -->
<update id="modify" parameterType="User">
update smbms_user
<trim prefix="set" suffixOverrides="," suffix="where id = #{id}">
<!-- prefix:前缀，在将下面的句子连接前添加，这里添加为’set‘
suffixOverrides：后缀覆盖，即将下面的句子连接后的最后一个’，‘,替换成’where id=#{id}‘
suffix：要替换成的句子
这里连接的句子为:update smbms_user set userCode = ?,...,modifyDate = ? where id = ?
-->
<if test="userCode != null">userCode=#{userCode},</if>
<if test="userName != null">userName=#{userName},</if>
<if test="userPassword != null">userPassword=#{userPassword},</if>
<if test="gender != null">gender=#{gender},</if>
<if test="birthday != null">birthday=#{birthday},</if>
<if test="phone != null">phone=#{phone},</if>
<if test="address != null">address=#{address},</if>
<if test="userRole != null">userRole=#{userRole},</if>
<if test="modifyBy != null">modifyBy=#{modifyBy},</if>
<if test="modifyDate != null">modifyDate=#{modifyDate},</if>
</trim>
</update>6、 动态条件查找数据-foreach-array
<!-- 根据用户角色列表，获取该角色列表下用户列表信息-foreach_array -->
<select id="getUserByRoleId_foreach_array" resultMap="userMapByRole">
select * from smbms_user where userRole in
<!--
foreach：迭代一个集合，通常用于in查询
collection：array|list|map-key（必须指定）
item:迭代子项，与#{roleIds}对应，
open：句子组合开始符
separator：句子组合分隔符
close：句子组合结束符
-->
<foreach collection="array" item="roleIds" open="(" separator="," close=")">
#{roleIds}
</foreach>
</select>7、 动态条件查找数据-foreach-list
<!-- 根据用户角色列表，获取该角色列表下用户列表信息-foreach_list -->
<select id="getUserByRoleId_foreach_list" resultMap="userMapByRole">
select * from smbms_user where userRole in
<!--
foreach：迭代一个集合，通常用于in查询
collection：array|list|map-key（必须指定）
item:迭代子项，与#{roleIds}对应，
open：句子组合开始符
separator：句子组合分隔符
close：句子组合结束符
-->
<foreach collection="list" item="roleIdList" open="(" separator="," close=")">
#{roleIdList}
</foreach>
</select>8、 动态条件查找数据-foreach-map
<!-- 根据用户角色列表，获取该角色列表下用户列表信息-foreach_map -->
<select id="getUserByRoleId_foreach_map" resultMap="userMapByRole">
select * from smbms_user where userRole in
<!--
foreach：迭代一个集合，通常用于in查询
collection：array|list|map-key（必须指定,map-key对应传入map的key值）
item:迭代子项，与#{roleIds}对应，
open：句子组合开始符
separator：句子组合分隔符
close：句子组合结束符
-->
<foreach collection="mKey" item="roleIdMap" open="(" separator="," close=")">
#{roleIdMap}
</foreach>
</select>9、 动态条件查找数据-trim-choose
<!-- 查询用户列表(choose) -->
<select id="getUserList_choose" resultType="User">
select * from smbms_user
<trim prefix="where" prefixOverrides="and|or">
<!-- choose类似于switch，从上往下，当满足条件时break(最多连接一条语句)，如果全都不满足条件则otherwise -->
<choose>
<when test="userName != null and userName != ''">
and userName like CONCAT ('%',#{userName},'%')
</when>
<when test="userCode != null and userCode != ''">
and userCode like CONCAT ('%',#{userCode},'%')
</when>
<when test="userRole != null">
and userRole = #{userRole}
</when>
<otherwise>
<!-- and YEAR(creationDate = YEAR(NOW()) -->
and YEAR(creationDate) = YEAR(#{creationDate})
</otherwise>
</choose>
</trim>
</select>10、动态条件查询用户列表-分页查询
<!-- 查询用户信息（分页显示） -->
<select id="getUserListByPaging" resultType="User">
select u.*, r.roleName from smbms_user u, smbms_role r
where u.userRole = r.id
<if test="userRole != null">
and u.userRole = #{userRole}
</if>
<if test="userName != null and userName != ''">
and u.userName like CONCAT ('%',#{userName},'%')
</if>
<!--
limit x,y
y:显示条数，即每页显示条数
x:显示起始位置
如:limit 0,5 则从第0条开始显示接下来5条记录
limit 5,5 则从第5条开始，显示接下来的5条记录
...
-->
order by u.creationDate DESC limit #{from}, #{pageSize}
</select>@Author: 瞌睡虫
@mybatis-3.2.2
@Database: mysql 5.7.15
@Tool: MyEclipse