How can multiple fields be updated in batches in MySQL?

In MySQL, you can use the UPDATE statement to update multiple fields in bulk. The general syntax of the UPDATE statement is as follows:

UPDATE 表名
SET 字段1 = 值1, 字段2 = 值2, ...
WHERE 条件;

The SET clause is used to specify the fields and their corresponding values to be updated, and can update multiple fields at the same time. The WHERE clause is used to specify the conditions for updating. If the WHERE clause is not specified, the corresponding fields of all records in the table will be updated to the specified value.

Here is an example: suppose there is a table called customers, with three fields: id, name, and age. Now we want to update the names and ages for all customers under the age of 30 to new values.

UPDATE customers
SET name = '新名字', age = 30
WHERE age < 30;

The UPDATE statement above will update the names of all customers in the customers table who are under 30 years old to ‘New Name’, and their age to 30.

It is important to note that the UPDATE operation will modify the data in the table, so use the UPDATE statement carefully and make sure to correctly set the WHERE clause to limit the scope of the update.