mybatis中foreach标签是迭代，那什么标签是能叠加条件的

现在的情况是，我在jsp页面上做了一个多选的下拉框，然后我在mapper中写的是

and CompTypeCode in
open="(" separator="," close=")">
#{item}


后来我发现，后面选的一个会把前面的那个选择条件替换掉，我现在是想选中几个就能有几个查询的条件，要什么弄

""
""
""
AND name = #{studentName}
""
""
AND number = #{studentNumber}
""
""
" "
AND ageid = #{age.ageId}
""
""
""
" "
AND genderid = #{gender.genderId}
""
""
""
""
AND majorid = #{major.majorId}
""
""
""
""
把引号去掉，不加引号标签放不上去，不知道这加上引号能不能放上去

AND name = #{studentName}


AND number = #{studentNumber}



AND ageid = #{age.ageId}




AND genderid = #{gender.genderId}




AND majorid = #{major.majorId}

还是放不上去，用where和if标签