~~~ <!-- 动态sql 之where<> and if --> <select id="selDS4" resultType="cn.li.pojo.Employee"> select * from employee <where> <if test="name!=null"> name like '%${name}%' </if> <if test="address!=null"> and address='${address}' </if> </where> </select> <!-- 动态sql 之trim and if --> <select id="selDS5" resultType="cn.li.pojo.Employee"> select * from employee <trim prefix="WHERE" prefixOverrides="and /or "> <if test="name!=null"> name like '%${name}%' </if> <if test="address!=null"> and address=#{address} </if> </trim> </select> <!-- 动态sql 之set --> <update id="selDS6"> update employee <set> <if test="name!=null"> name=#{name}, </if> <if test="address!=null"> address=#{address} </if> </set> where id=#{id} </update> <!-- 动态sql 之trim和set --> <update id="selDS7"> update employee <trim prefix="SET" suffixOverrides=","> <if test="name!=null"> name=#{name}, </if> <if test="address!=null"> address=#{address} </if> </trim> where id=#{id} </update> ~~~