mybatis动态新增(insert)和修改(update)方式

<insert id="saveDynamicCow" useGeneratedKeys="true" keyProperty="intCowId">
        insert into cowtest
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="intPastureId != null and '' != intPastureId">
                intPastureId,
            </if>
            <if test="varCowCode != null and '' != varCowCode">
                varCowCode,
            </if>
            <if test="cSex != null and '' != cSex">
                cSex,
            </if>
            <if test="addSource != null and '' != addSource">
                addSource,
            </if>
            <if test="sireClass != null and '' != sireClass">
                sireClass,
            </if>
            <if test="dateLeave != null and '' != dateLeave">
                dateLeave,
            </if>
            <if test="intLeaveClass != null and '' != intLeaveClass">
                intLeaveClass,
            </if>
            <if test="intReason != null and '' != intReason">
                intReason,
            </if>
            <if test="intCurBar != null and '' != intCurBar">
                intCurBar,
            </if>
            <if test="intCurBarName != null and '' != intCurBarName">
                intCurBarName,
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="intPastureId != null and '' != intPastureId">
                #{intPastureId},
            </if>
            <if test="varCowCode != null and '' != varCowCode">
                #{varCowCode},
            </if>
            <if test="cSex != null and '' != cSex">
                #{cSex},
            </if>
            <if test="addSource != null and '' != addSource">
                #{addSource},
            </if>
            <if test="sireClass != null and '' != sireClass">
                #{sireClass},
            </if>
            <if test="dateLeave != null and '' != dateLeave">
                #{dateLeave},
            </if>
            <if test="intLeaveClass != null and '' != intLeaveClass">
                #{intLeaveClass},
            </if>
            <if test="intReason != null and '' != intReason">
                #{intReason},
            </if>
            <if test="intCurBar != null and '' != intCurBar">
                #{intCurBar},
            </if>
            <if test="intCurBarName != null and '' != intCurBarName">
                #{intCurBarName},
            </if>
        </trim>
   </insert>

<update id="updateDynamicCow">
        update cowtest
        <trim prefix="SET" suffixOverrides=",">
            <if test="dateBirthDate != null and '' != dateBirthDate">
                dateBirthDate= #{dateBirthDate},
            </if>
            <if test="decBirWeight != null and '' != decBirWeight">
                decBirWeight= #{decBirWeight},
            </if>
            <if test="decQuotiety != null and '' != decQuotiety">
                decQuotiety= #{decQuotiety},
            </if>
            <if test="intCurBar != null and '' != intCurBar">
                intCurBar= #{intCurBar},
            </if>
            <if test="intCurBarName != null and '' != intCurBarName">
                intCurBarName= #{intCurBarName},
            </if>
            <if test="intCurFetal != null and '' != intCurFetal">
                intCurFetal= #{intCurFetal},
            </if>
            <if test="intBreed != null and '' != intBreed">
                intBreed= #{intBreed},
            </if>
            <if test="cSex != null and '' != cSex">
                cSex= #{cSex},
            </if>
        </trim>
        where varCowCode= #{varCowCode}
    </update>

public class Teacher {

    private int teacherId;//教师Id

    private String teacherName;//教师名

    private int count;//mybatis判断Id是否存在

    public int getTeacherId() {
        return teacherId;
    }

    public void setTeacherId(int teacherId) {
        this.teacherId = teacherId;
    }

    public String getTeacherName() {
        return teacherName;
    }

    public void setTeacherName(String teacherName) {
        this.teacherName = teacherName;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

}

<insert id="AddTeacher" parameterType="com.mycompany.entity.Teacher">
        <selectKey keyProperty="count" resultType="int" order="BEFORE">
            select count(*) from Teacher where teacher_id = #{teacherId}
        </selectKey>
        <if test="count > 0">
            update event
            <set>
               <if test="teacherName!= null" >  
                    teacher_name= #{teacherName},
               </if>
            </set>
            <where>
                teacher_id = #{teacherId}
            </where>
        </if>
        <if test="count==0">
            insert into teacher(teacher_id,teacher_name) values (#{teacherId},#{teacherName})
        </if>
</insert>