Understanding Common MySQL Errors

Common MySQL Errors and Examples

Errors and blunders are ubiquitous in many aspects of life, and that includes when using MySQL. Using MySQL or any other database does not ensure an error-free environment so it’s only natural that you encounter these kinds of errors along the way but worry not, this guide could help you out by enlisting the most common errors on MySQL database.

In this post, we'll look at the structure of MySQL errors and how to understand them. 

We've also selected the top ten most common MySQL problems, along with their 

descriptions.

The anatomy of MySQL errors

Each MySQL error has the following components that identify the issue:
  • The Mistake NUMBER is a one-of-a-kind number that identifies each error.
  • SQLSTATE is a code that is used to identify SQL error circumstances.
  • ERROR MESSAGE is a human-readable description of the error.

Here's an example of a MySQL error:

ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist

In this example we’ll dissect what the error above is:

  • 1146 is the ERROR NUMBER
  • 42S02 is the SQLSTATE
  • Table 'test.no_such_table' doesn't exist is the ERROR MESSAGE

Common MySQL Errors

ERROR 1045 (HY000): Access denied for user 'root'@'localhost' (using password: YES)

Anyone who uses MySQL has undoubtedly seen this at least once. This error can be caused by a variety of factors, including an incorrect username and/or password or a lack of database permissions.

ERROR 2013: Lost connection to MySQL server during query

When the connection between your MySQL client and database server times out, this error occurs. Essentially, the query took too long to produce data, therefore the connection was terminated.

ERROR 1040: Too many connections

This error indicates that other customers are using all available connections.

ERROR 2006 (HY000): MySQL server has gone away

The most likely cause of this error is that the server timed out and disconnected the connection. If nothing happens after 8 hours, the server will automatically disconnect the connection.

ERROR 2008: MySQL client ran out of memory

This indicates that MySQL lacks sufficient memory to store the complete query result.

ERROR 1114 (HY000): The table is full

If a table-full error occurs, the disk may be full or the table has reached its maximum size. The practical maximum table size for MySQL databases is typically governed by operating system file size restrictions rather than by MySQL internal limits.

ERROR 1064 (42000): You have an error in your SQL syntax

This signifies that MySQL is unable to interpret your query due to a syntax error. Typically, the root of the problem is a failure to wrap some literals or values in backticks or quotes. In a MySQL query, for example, the name of your database should be 'my-database' rather than my-database.

The error notice will even go so far as to indicate where the syntax begins to be erroneous, which you may use as a starting point to track out the problem.

ERROR: Packet too large

When a MySQL client or server receives a packet that is larger than the max allowed packet bytes, it returns a Packet too large error and ends the connection.

The maximum packet size that can be transferred to or from the MySQL server or client is 1 GB. If the MySQL server or client gets a packet larger than max allowed packet bytes, it generates an ER NET PACKET TOO LARGE error and terminates the connection.

ERROR: Communication Errors and Aborted Connections

If you see any of the following problems in your error log.

010301 14:38:23  Aborted connection 854 to db: 'users' user: 'username'

This signifies that one of the following has occurred:

  • Before exiting, the client application did not call mysql_close().
  • The client had been asleep for longer than the wait timeout or interactive timeout, with no requests made.
  • The client program unexpectedly terminated in the middle of the transfer.
ERROR: Can’t create/write to file

This indicates that MySQL cannot create a temporary file in the temporary directory for the result set if we get the following error while executing a query.

ERROR: Commands out of sync

If you get this error in your client code, it means that you are calling client functions in the incorrect sequence. For example, if you use mysql_use_result() and try to execute a new query before you call mysql_free_result().

Conclusion

Hopefully, this article has given you an understanding of how to use MySQL and alerted you to some common errors you might receive when using it. While these errors can often be resolved easily, and the time taken to do so may not be extensive, it is still important to have a general understanding of what is happening to your host. And who knows? Some day you may encounter these errors and with this knowledge, it can save you from a lot of headaches, and speaking of avoiding headaches, try Ottomatik for a stress-free database automated management and save yourself a lot of unwanted errors and problems while managing your database!

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