Mybatis （三）
Mybatis SQL映射文件解析
参考文章：http://www.mybatis.org/mybatis-3/zh/sqlmap-xml.html
MyBatis 的真正强大在于它的映射语句，也是它的魔力所在。由于它的异常强大，映射器的 XML 文件就显得相对简单。如果拿它跟具有相同功能的 JDBC 代码进行对比，你会立即发现省掉了将近 95% 的代码。MyBatis 就是针对 SQL 构建的，并且比普通的方法做的更好。
增删改查 的xml 配置
- 增
<insert id="addEmp">
insert into hr_o_employee (employee_ID ,employeeName,gender,email)
values(#{employee_ID},#{employeeName},#{gender},#{email})
insert>
<insert id="addEmpForId" useGeneratedKeys="true" keyProperty="id">
insert into hr_o_employee (employee_ID ,employeeName,gender,email)
values(#{employee_ID},#{employeeName},#{gender},#{email})
insert>
对于不支持自动生成类型的数据库或可能不支持自动生成主键的 JDBC 驱动，MyBatis 有另外一种方法来生成主键。
<insert id="insertAuthor">
<selectKey keyProperty="id" resultType="int" order="BEFORE">
select CAST(RANDOM()*1000000 as INTEGER) a from SYSIBM.SYSDUMMY1
selectKey>
insert into Author
(id, username, password, email,bio, favourite_section)
values
(#{id}, #{username}, #{password}, #{email}, #{bio}, #{favouriteSection,jdbcType=VARCHAR})
insert>
- 删
<delete id="delete">
delete from hr_o_employee where employee_id=#{employee_ID}
delete>
- 改
<update id="update">
update hr_o_employee set employeeName=#{employeeName} where employee_ID=#{employee_ID}
update>
- 查询：单个参数
<select id="getEmp" resultType="com.myt.bean.Employee">
select * from hr_O_Employee where employee_id = #{employee_id}
select>
- 查询：多个参数
<select id="getEmpByMore" resultType="com.myt.bean.Employee">
select * from hr_O_Employee where employee_id = #{0} and employeeName=#{1}
select>
<select id="getEmpByMore" resultType="com.myt.bean.Employee">
select * from hr_O_Employee where employee_id = #{empid} and employeeName=#{eName}
select>
<select id="getEmpByMore" resultType="com.myt.bean.Employee">
select * from hr_O_Employee where employee_id = #{employee_ID} and employeeName=#{employeeName}
select>
<select id="getEmpByMore" resultType="com.myt.bean.Employee">
select * from hr_O_Employee where employee_id = #{empid} and employeeName=#{eName}
select>