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SQL update batch update

2022-06-27 18:36:00 【Ink Sky Wheel】

First review ,sql update Statement is used to modify data in a table .

grammar ：

UPDATE The name of the table SET Column name = The new value WHERE Column name = Certain value

SQL update Batch update instance

1、 Through the same table update Copy column to another column , As shown in the figure below , Add columns to the original table score2, And score Copy the value of

The statement is as follows ：

update student set score2= score

Output results

What if the data of different tables are updated ？ How to operate ？ Please look down ~

2、 Under special circumstances , A table needs to add a column foreign key to another table （ It could be a table from another library ） relation , This situation has no relevance , We often use paper-based materials to make spreadsheets and then temporary tables to update relational data in batches

Such as student surface , You need to add columns grade_id

Another temporary table Grade surface （ It may be a temporary table imported from a spreadsheet ） as follows ：

Current demand in student Added to the table Grade_id Corresponding assignment , The statement is as follows ：

update student 
set grade_id = (select grade_id from grade a where a.student_id=student.id) 
where student.id in (select student_id from grade)

The output is as follows ：

Summary ：

sql update Batch update , It mainly uses the associated sub query to update the corresponding relationship , It should be noted that the corresponding relationship between the two table values and the condition range .

update There are risks , Be careful in operation ！ friends

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