mysql error message

MySQL error message

MySQL is an open source relational database management system that is widely used in web development, data analysis and other fields. However, when using MySQL, you may encounter various error messages, causing database operations to fail. This article will introduce common MySQL error messages and their solutions.

1. Connection error

When trying to connect to MySQL, you may encounter the following error message:

1) 1045 - Access denied for user 'user_name'@'localhost ' (using password: YES)

indicates that the connection is refused. The user name or password may be incorrect, or the user does not have permission to log in to MySQL.

Solution:

Check whether the user name and password are correct;
Check whether the user is authorized to log in to MySQL;
Try to log in to MySQL using the root user.

2) 2002 - Can't connect to local MySQL server through socket '/var/run/mysqld/mysql.sock' (2)

means that it cannot connect to the MySQL server. It may be because the MySQL server has not been started, the MySQL server socket file does not exist, or the host name, port number and other information in the MySQL server configuration file are incorrect.

Solution:

Check whether the MySQL server has been started;
Check whether the MySQL server socket file exists;
Check the host name and port number in the MySQL server configuration file Wait for the information to be correct.

2. Query error

When executing a SQL query, you may encounter the following error message:

1) 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'xxx' at line xxx

indicates a SQL syntax error, which may be due to incorrect writing of the SQL statement, illegal characters in the SQL statement, or The function or keyword in the file is incorrectly used.

Solution:

Check the SQL syntax carefully to ensure there are no writing errors;
Check whether there are illegal characters in the SQL statement;
Check whether the functions or keywords in the SQL statement are used mistake.

2) 1054 - Unknown column 'column_name' in 'table_name'

means that the queried column name or table name does not exist. This may be because the column name or table name is written incorrectly, the column name or The table name was deleted or renamed, etc.

Solution:

Check whether the queried column name or table name is correct;
Check whether the column or table has been deleted or renamed.

3. Data processing errors

When performing data processing on the MySQL database, you may encounter the following error message:

1) 1062 - Duplicate entry 'xxx' for key 'unique_index_name'

means that a duplicate key value error occurs when inserting or updating data, possibly because the inserted or updated key value already exists in the database.

Solution:

Check whether the key value already exists in the database;
Modify the data operation to ensure that the key value is unique.

2) 1265 - Data truncated for column 'column_name' at row xxx

indicates data overflow or truncation. It may be that the data length exceeds the length defined by the table field when inserting or updating data.

Solution:

Check the table field definition to ensure that the data length is less than or equal to the length of the table field definition;
Repair the data operation and ensure that the data length conforms to the table field definition.

4. Permission errors

When performing database operations, you may encounter the following permission errors:

1) 1142 - SELECT command denied to user 'user_name'@' localhost' for table 'table_name'

means that the user does not have permission to query the table.

Solution:

Grant the user permission to query the table.

2) 1216 - Cannot add or update a child row: a foreign key constraint fails

Indicates that the foreign key constraint is violated, possibly because the conflict between tables is violated when inserting or updating data associated conditions.

Solution:

Check the violated foreign key constraints;
Repair the data operation to ensure that the foreign key constraints are met.

Summary

MySQL error messages may affect the normal operation of the database, so you should read the error messages carefully and take corresponding solutions in a timely manner to ensure the normal operation of the MySQL database. At the same time, when performing database operations, you must also pay attention to following rules such as data type definitions, constraints, and permission control to avoid possible errors.

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