What does the mysql update statement return?

Mysql update statement returns an integer value representing the number of modified rows, telling the operator how many rows of data have been updated. The UPDATE statement will only modify rows that meet the conditions, and only return the final number of modified rows. , usually, the update operation will return an integer value greater than or equal to 0. If the return value is 0, it means that no rows that meet the update conditions have been modified.

Operating system for this tutorial: Windows 10 system, MySQL 8 version, Dell G3 computer.

In MySQL, the UPDATE statement is used to modify data in the table. When an UPDATE statement is executed, it returns an integer value representing the number of rows that were modified. This return value tells you how many rows of data were updated.

Normally, the update operation returns an integer value greater than or equal to 0. This indicates how many rows of data were successfully modified. If the return value is 0, it means that no rows that meet the update conditions have been modified.

The following is an example that shows the use of the UPDATE statement and obtains the return value:

UPDATE table_name SET column1 = value1 WHERE condition;

Suppose there is a table named users, which contains three columns: id, name, and age. We can use the UPDATE statement to change the names of all users older than 30 years old to "John" and get the number of updated rows returned:

UPDATE users SET name = 'John' WHERE age > 30;

At this time, if there are 5 rows of data with an age greater than 30 years old, Then the UPDATE statement will return a value of 5, indicating that 5 rows of data have been successfully modified.

It should be noted that the UPDATE statement will only modify rows that meet the conditions, and only return the final number of modified rows. If the UPDATE statement did not modify any rows, it will still return 0 instead of an error.

Update operations can affect the data in the database, so you need to carefully consider the conditions and update content when using the UPDATE statement to avoid unexpected results on the data.

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