Hey there! Let's dig into why your update/delete statements aren't sticking in MySQL—both in JDBC and DBeaver. This is a super common gotcha, so let's break down the most likely causes and fixes step by step:

1. You're Not Committing Transactions (Top Suspect!) #

JDBC defaults to manual transaction mode, meaning any changes you make (like DELETE or UPDATE) only live in memory until you explicitly commit them. If you skip calling connection.commit() after executing statements, those changes will never sync to the database.

• Fix for JDBC:
  Either enable auto-commit when initializing your connection:

  connection.setAutoCommit(true);
  

  Or explicitly commit right after your update operations:

  stmt.executeUpdate("DELETE FROM your_table WHERE id = 1");
  connection.commit(); // Don't forget this critical line!
  

• Fix for DBeaver:
  DBeaver often uses manual transaction mode by default. After running your statements, click the "Commit" button (usually a checkmark icon) in the toolbar. Or tweak your connection settings to enable "Auto-commit" so changes save immediately.

2. Insufficient MySQL User Permissions #

If your MySQL account lacks the right permissions to modify tables, even valid SQL will fail silently or throw errors.

• Check permissions: Run this query in MySQL command line or DBeaver:

  SHOW GRANTS FOR 'your_username'@'your_host';
  

  Look for permissions like UPDATE, DELETE, or ALTER (depending on your operation). If they're missing, ask your admin to grant them:

  GRANT UPDATE, DELETE ON your_database.your_table TO 'your_username'@'your_host';
  FLUSH PRIVILEGES;
  

3. SQL Statement Issues (Especially the Third One) #

If the third statement won't even run in IDEA, it's almost certainly a syntax error or invalid reference:

• Double-check typos in table/column names (MySQL is case-sensitive on Linux/macOS—make sure your case matches the actual schema).
• Verify syntax (e.g., missing commas, broken WHERE clauses, or using MySQL-specific functions without proper settings).
• Test the exact statement directly in MySQL command line—if it fails there too, you'll get a clear error message explaining the problem.

4. Connection Configuration Problems #

Double-check your JDBC URL for settings that block modifications:

• Did you accidentally add readOnly=true? That locks the connection to read-only mode.
• Example of a problematic URL:

  jdbc:mysql://localhost/your_db?readOnly=true
  

• Fix it by removing the parameter or setting readOnly=false.

5. Locking or Transaction Isolation Issues #

If another transaction holds a lock on the table/rows you're targeting, your statements might hang or appear to do nothing.

• Check for locks: Run this query to inspect active locks:

  SHOW ENGINE INNODB STATUS;
  

  Look for sections about transaction locks—if you see pending locks, you might need to kill the blocking transaction or adjust your isolation level.

Quick Troubleshooting Steps to Narrow It Down #

• First, test your SQL directly in MySQL command line. If it works there, the issue is with JDBC/DBeaver setup. If not, it's a SQL/permission problem.
• Enable JDBC logging to see exactly what SQL is sent to MySQL—sometimes frameworks modify your queries unexpectedly.
• In DBeaver, check the "Error Log" tab (usually at the bottom) for hidden error messages that don't pop up in the main window.

内容的提问来源于stack exchange，提问作者Udaltsov Sergey