When developing using PHP, we often encounter situations where we need to update data in the database. Usually, we need to update the data through the UPDATE statement, and in the process of updating the data, we may encounter such a problem: the data is updated, but the data does not change when querying. Why is this?
There are many reasons for this problem. Let’s analyze the possible reasons one by one.
1. Caching problem
When performing a database query, PHP will enable caching by default. If the data is not synchronized to the cache in time when we perform an update operation, then when we perform a query operation , the old data in the cache will be read, resulting in the phenomenon that the data has not changed. Therefore, we need to clear the cache in time when updating data, or turn off the cache.
2. Transaction issue
If a transaction is used when updating data, then we need to see the updated results only after the transaction is committed. Therefore, when we perform data queries, we need to ensure that these query statements are within the same transaction and that the transaction has been successfully submitted.
3. Code Error
When we perform a data update operation, if there is an error in the code, the update may not be successful. In this case, we need to check if there are any errors in the code and need to perform error handling while executing the operation. If an error occurs, we need to record the error information promptly and eliminate the error.
4. Field type problem
If we update the types of some fields in the database during the process of updating data, then when querying, due to different types, the query results will be A problem occurs, resulting in data not being queried. In this case, we need to determine if the field type is correct and adjust accordingly.
In short, after updating the data, if we find that the data has not been updated correctly, we need to first confirm whether the above situations have occurred, and then gradually troubleshoot the problem. At the same time, we also need to pay attention to code specifications and security during code writing and database operations to avoid data loss and security issues.
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