Change One Cell's Data in mysql

How can I change the data in only one cell of a mysql table. I have problem with UPDATE because it makes all the parameters in a column change but I want only one changed. How?

You probably need to specify which rows you want to update...

UPDATE 
    mytable
SET 
    column1 = value1,
    column2 = value2
WHERE 
    key_value = some_value;

My answer is repeating what others have said before, but I thought I'd add an example, using MySQL, only because the previous answers were a little bit cryptic to me.

The general form of the command you need to use to update a single row's column:

UPDATE my_table SET my_column='new value' WHERE something='some value';

And here's an example.

BEFORE

mysql> select aet,port from ae;
+------------+-------+
| aet        | port  |
+------------+-------+
| DCM4CHEE01 | 11112 | 
| CDRECORD   | 10104 | 
+------------+-------+
2 rows in set (0.00 sec)

MAKING THE CHANGE

mysql> update ae set port='10105' where aet='CDRECORD';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

AFTER

mysql> select aet,port from ae;
+------------+-------+
| aet        | port  |
+------------+-------+
| DCM4CHEE01 | 11112 | 
| CDRECORD   | 10105 | 
+------------+-------+
2 rows in set (0.00 sec)

UPDATE will change only the columns you specifically list.

UPDATE some_table
SET field1='Value 1'
WHERE primary_key = 7;

The WHERE clause limits which rows are updated. Generally you'd use this to identify your table's primary key (or ID) value, so that you're updating only one row.

The SET clause tells MySQL which columns to update. You can list as many or as few columns as you'd like. Any that you do not list will not get updated.

UPDATE only changes the values you specify:

UPDATE table SET cell='new_value' WHERE whatever='somevalue'