What is the reason for the failure of addition, deletion and modification in php? How to deal with it?

In PHP, we often encounter problems such as addition, deletion and modification failure. There are many reasons for this problem. This article will analyze some of the common reasons to help readers solve this problem.

1. SQL statement error

When using PHP to perform addition, deletion, and modification operations, it is often necessary to use SQL statements to complete the operation. If the SQL statement is written incorrectly, the operation will fail. Common errors include spelling errors, grammatical errors, missing quotation marks, and more. If you encounter this problem, you can troubleshoot the problem by printing the SQL statement and executing it manually in the database.

2. The data table does not exist

Another common problem is that the data table does not exist. If you try to add, delete or modify a data table that does not exist, it will fail. This problem is usually caused by you writing the wrong table name in the SQL statement, or not correctly specifying the database, table name and other information when using PHP's database functions.

3. Primary key conflict

When you try to insert the same data into an existing primary key, you will encounter the problem of primary key conflict. This problem is usually caused by you not correctly defining the primary key or unique index constraints when designing the database, or not correctly handling primary key conflicts when writing the code. When encountering this problem, you can use the ON DUPLICATE KEY UPDATE statement in the SQL statement to solve it.

4. Field type mismatch

When you insert string type data into a Boolean type field, or insert floating point type into an integer type field When using data, you will encounter the problem of field type mismatch. This problem is usually caused by you not correctly defining field types when designing the database, or not properly handling field type mismatches when writing code. The way to solve this problem is to convert the data into the correct type in the SQL statement, or to judge and convert the data type in the code.

5. Insufficient Permissions

The last common reason is insufficient permissions. If you try to operate in a data table that does not have access rights, or if you use a user without sufficient rights to insert data into the database, it will fail. This problem is usually caused by you not correctly granting the user enough permissions in the database. The solution to this problem is to grant the user sufficient permissions in the database, or to use a user with sufficient permissions to operate.

Summary

Failure to add, delete or modify is a relatively common problem. When solving this problem, you need to carefully check the SQL statement, data table, field type and other aspects. If you encounter this problem, you can refer to some common causes described in this article and troubleshoot the problem one by one. At the same time, in daily development, you should also do a good job in database design and code writing to avoid such errors in the later stage.

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