Mysql _mysql The SQL statement that copies the contents of one of a table's fields to a field in another table.

Requirements: Copy one of the field contents of a table to a field in another table.

Implementing SQL Statement 1:

Copy Code code as follows:

UPDATE File_manager_folder F1
Left OUTER JOIN file_manager_folder F2
On f1.name = F2.name and F2.parentid = 54
SET F1.parentid = 54
WHERE F2.name is NULL and f1.id in (1,2,3);

Implementing SQL Statement 2:

Copy Code code as follows:

Update B Set extra = A.extra from join B on (a.id = b.id);

Implementing SQL Statement 3:

Copy Code code as follows:

Update B Set b.sms = (select A.sms from a WHERE a.id = b.ID)

You need to determine that the IDs in the two tables are primary keys or unique

Implementing SQL Statement 4:

Copy Code code as follows:

UPDATE A SET a.sms = (select b.sms from b where a.id = b.id) WHERE EXISTS (select 1 from b where a.id = b.ID);

Implementing SQL Statement 5:
To copy one table field data to another, you can write this:
Implementing SQL Statement 5:

Copy Code code as follows:

UPDATE tb_1 INNER JOIN tb_2 on tb_1.tid = Tb_2.tid
SET tb_1.tcontent = tb_2.tcontent

Attached: copy of same table

Requirements: Copy the contents of one field from the same table to another field

Example 1:
I want to copy the contents of a field from the article table to the B field in the article table. The SQL statement is:

Copy Code code as follows:

Update article set b=a;

Example 2:
Sometimes we need to copy a whole column of data from one field to another in a new field, which is simple, SQL can write:

Copy Code code as follows:

UPDATE tb_1 SET content_target = Content_source;

The general wording is as follows:

Copy Code code as follows:

Update {your_table} set {Source_field} = {Object_field} WHERE cause