I have a database table populated with 10k rows of data. A great deal of those rows have null values in specific columns. How do I replace this null value with for instance the empty string for a string column?

I'm looking for the *easiest* way to do this since this operation will only need to be performed *once*.

**What I have tried:**

```
UPDATE tablename set mycolumn='' where mycolumn is null;

```

This gives me the following error:

> 
> Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column To disable safe mode, toggle the option in Preferences -> SQL Editor and reconnect.
> 
> 
> 

I am not the administrator of the database, so I cannot disable safe mode.

```
UPDATE tablename set mycolumn=''
  where Id in (SELECT Id FROM tablename where mycolumn is null);

```

This gives me the following error:

> 
> Error Code: 1093. You can't specify target table 'tablename' for update in FROM clause.
> 
> 
> 

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**Note:**

In the examples above I have substituted the real tablename and column-name with placeholders.