Why Does My MySQL UPDATE Query Return \'0 Rows Affected\'?

Troubleshooting "0 Rows Affected" Error in MySQL UPDATE Queries

When executing an UPDATE query that seemingly should modify data in a MySQL table, but instead results in "0 rows affected," it can be perplexing. One potential cause for this error is when the new value being assigned matches the existing value.

In the provided code:

UPDATE phonecalls 
   SET Called = "Yes" 
 WHERE PhoneNumber = "999 29-4655"

It's attempted to update the "Called" column to "Yes" where the "PhoneNumber" column has the value "999 29-4655." However, if "Called" is already set to "Yes" for that record, the query won't make any changes and will return "0 rows affected."

To avoid this issue, consider checking the current value of the "Called" column before executing the UPDATE query. Ensure the new value you're trying to assign is different from the existing value to trigger an actual data modification.

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