SQLSTATE[42000]: Syntax Error or Access Conflict: 1075 Table Definition Incorrect; Only One Auto Column Allowed and It Must Be Defined as a Key

This error message indicates that there is a problem with the table definition in a SQL query. Specifically, the error message states that there can only be one auto column and that this column must also be defined as a key.

The auto column is an automatically generated column that assigns each new row a unique identifier. This column is often used as a primary key that other tables can reference.

To resolve this error message, check the table's definition and ensure that there is only one auto column defined and that it is also defined as a key. If the problem persists, check the syntax of the SQL query to ensure that it is correctly formatted.

Here is an example of a correctly defined table with an auto column that is also defined as a key:

CREATE TABLE example_table (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    age INT
);

In this example, the "id" column is an auto column that is also defined as the primary key. This ensures that each row in the table has a unique identifier and that other tables can reference this table by the "id" column.