Question

这是我的查询，用于比较两个表并获取另一个表中不存在的人的数据

def article_detail(request, pk):
    article = get_object_or_404(Article, pk=pk)
    # sections and current_section

    if article.block.name == "Action" and request.user.username not in  administors:
        raise  Http404("You are not authorized to read Section Action,I prefert to communicate on the topic action in persion.")

但是，由于我们有大约8000个人数据，因此该查询需要执行近1分钟的时间，对于每一行，它应该与其他表数据进行检查。

我对此有其他选择吗？

编辑： BRvaja的评论有效，创建索引后，它可以快速加载数据

SELECT 
    id,
    registrationnumber,
    CONCAT(name, ' ', surname) name,
    admissionclass,
    section
FROM
    studentsdata
WHERE
    registrationnumber NOT IN (SELECT 
            reg_number
        FROM
            attendance);

Answer 1

SELECT 
    id,
    registrationnumber,
    CONCAT(name, ' ', surname) name,
    admissionclass,
    section
FROM
    studentsdata
        LEFT JOIN
    attendance ON studentsdata.registrationnumber = attendance.reg_number
WHERE
    attendance.reg_number IS NULL

Answer 2

尝试这个

SELECT 
    st.id,
    st.registrationnumber,
    CONCAT(st.name, ' ', st.surname) name,
    st.admissionclass,
    st.section
FROM
    studentsdata as st
        INNER JOIN
    attendance as at ON st.registrationnumber != at.reg_number

mysql查询花费比预期更长的时间

2 个答案: