how to add a new column every time i run a python program

前端 未结 1 1010
孤城傲影
孤城傲影 2021-01-26 05:26

i want my table to have 1st column as roll no,second as name.whenever i run python program i want to add a column of date in table.and in that new column i want to populate the

相关标签:
1条回答
  • 2021-01-26 06:21

    Don't change your DB design at runtime, but design it in a way that you will change the data not the structure.

    You could have two tables. One called Student with columns rollno and name, maybe PK on rollno if it is unique.

    Then have another table called Thing (any suitable name, but I don't know what your data is about) with three columns when (datetime), value (any suitable name) (CHAR(1)) and student (same type as rollno).

    Define PK over both when and value to ensure that each student has only one value per date. Define a FK from Thing.student to Student.rollno. Now your DB takes care of keeping your data (mostly) consistent.

    Define indices depending on your needs of selects, inserts and updates over the different columns.

    Then for querying join both tables to get the desired result, e.g.

    select s.name, t.value
    from Student s
    left join Thing t on t.student = s.rollno
    where t.when == 'whenever'
    

    (I am not sure about the mysql dialect, so maybe some more quotes are needed. Please feel free to edit.)

    0 讨论(0)
提交回复
热议问题