SQL新手，我试图弄清楚如何更新表，以便从特定数据集中删除重复项

We are trying to remove duplicates from our data set before we make the jump to a new system. The idea is to move all the data from the newer duplicate student to the original. We wrote a script that automatically moves all the information over but we're still trying to figure out how to optimize it and only move certain parts over. Each student has a school and sometimes the duplicates have the same school which is unnecessary. The school information is all in one table and we just update the parent_id to move the new to the old. How do we get it so that the transfer only takes the non-duplicate schools and since each is tied to a date, we want to make sure we keep the original if their is a duplicate school. What can we do?We are trying to remove duplicates from our dat