C＃sql将数据从一个表插入另一个表 [英] C# sql insert data from one table to another

问题描述

我的数据库中有两个表。

students_table和student_details表。

我需要从students_table获取所有学生姓名并将其插入student_details表中不存在如何做到这一点？

从students_table中选择姓名，
每个姓名
如果在student_details表中不存在而不是插入它。

所以，我用select查询填充数据表并获取所有值，如何在student_details表中插入它们。

I have two tables in my database.
students_table and student_details table.
I need to get all student names from students_table and insert them in student_details table if they already don't exist. how can this be done?
Select Name from students_table,
for each Name if it does not already exist in student_details table than insert it.
So, i populate a data table with select query and get all the values, how do i insert them in student_details table.

推荐答案

你应该复制ID而不是名。不要将名称用作ID;使用无意义的东西 - 比如整数或GUID。



有几种方法。一种方法是使用带有JOIN的INSERT / SELECT：

You should be copying IDs rather than names. Do not use names as IDs; use something meaningless -- like an integer or a GUID.

There are several ways. One way to do that is with an INSERT/SELECT with a JOIN:

INSERT INTO Child ( ID )
SELECT A.ID FROM Parent A
LEFT OUTER JOIN Child B
ON A.ID=B.ID
WHERE B.ID IS NULL

create table  student_details(roll int identity, name varchar(10));
insert into  student_details(name) values('A'), ('B');

create table  student_table(sl int identity, name varchar(10));
insert into  student_table(name) values('A'), ('B'), ('C'), ('D');

insert into student_details(name)
select name from  student_table where name not in(select name from student_details);

如果您使用sql server 2008或信件，那么您可以使用



if oracle then

If you use sql server 2008 or letter then you can use

if oracle then

insert into student_details(name)
select name from student_table
minus
select name from student_details

如果sql server那么

if sql server then

insert into student_details(name)
select name from student_table
except
select name from student_details

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