Setting value for one column of all records in table

Question

I'm trying to clear one column for all records in my table. For example, if my table had three columns: `id`, `comment`, and `likes` - I would like to be able to clear the `likes` column. ``` +---+-------+-----+ |id |comment|likes| +-----------------+ |1 |hi |3 | |2 |hello |12 | |3 |hey |1 | +---+-------+-----+ ``` so that afterwards it would look like this: ``` +---+-------+-----+ |id |comment|likes| +-----------------+ |1 |hi | | |2 |hello | | |3 |hey | | +---+-------+-----+ ``` I'm guessing I would have to use MySQL `UPDATE` to clear the `likes` value, but how do I iterate through all records and keep the `id` and `comment` fields the same? I don't want to change each record manually.

Accepted Answer

```
UPDATE your_table SET likes = NULL
```

or if your `likes` column does not allow `NULL`:

```
UPDATE your_table SET likes = ''
```

Some SQL tools that are used for executing DB queries prevent updates on ALL records (queries without a `where` clause) by default. You can configure that and remove that savety setting or you can add a `where` clause that is `true` for all records and update all anyway like this:

```
UPDATE your_table 
SET likes = NULL
WHERE 1 = 1
```

If you compare with `NULL` then you also need the `IS` operator. Example:

```
UPDATE your_table 
SET likes = NULL
WHERE likes IS NOT NULL
```

because comparing `NULL` with the equal operator (`=`) returns UNKNOWN. But the `IS` operator can handle `NULL`.

Setting value for one column of all records in table

Solution

Problem