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This article will explain in detail how to use MySQL fields in a table to update the fields in another table. Xiaobian thinks it is quite practical, so share it with you as a reference. I hope you can gain something after reading this article.

1, modify column 1

update student s, city cset s.city_name = c.namewhere s.city_code = c.code;

2, modify multiple columns

update a, bset a.title=b.title, a.name=b.namewhere a.id=b.id

·Subqueries

update student s set city_name = (select name from city where code = s.city_code);

Oracle queries return more than one row.

The database has multiple duplicates of data for your query.

For example:

UPDATE "SYS_ROLE" ASET A . "DEPT_ID" = ( SELECT c. "id" FROM "his_department_info" c WHERE c. "dept_name" = A . "ROLE_NAME"

If the above sql statement reports single-row subquery returns more than one row error, it indicates that table c "dept_name" and table A. These two fields of "ROLE_NAME" have duplicate data

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