How can I modify the size of column in a MySQL table?

I have created a table and accidentally put `varchar` length as `300` instead of `65353`. How can I fix that?

An example would be appreciated.

ALTER TABLE <tablename> CHANGE COLUMN <colname> <colname> VARCHAR(65536);

You have to list the column name twice, even if you aren't changing its name.

Note that after you make this change, the data type of the column will be `MEDIUMTEXT`.

---

Miky D is correct, the `MODIFY` command can do this more concisely.

---

Re the `MEDIUMTEXT` thing: a MySQL row can be only 65535 bytes (not counting BLOB/TEXT columns). If you try to change a column to be too large, making the total size of the row 65536 or greater, you may get an error. If you try to declare a column of `VARCHAR(65536)` then it's too large even if it's the only column in that table, so MySQL automatically converts it to a `MEDIUMTEXT` data type.

mysql> create table foo (str varchar(300));
mysql> alter table foo modify str varchar(65536);
mysql> show create table foo;
CREATE TABLE `foo` (
`str` mediumtext
) ENGINE=MyISAM DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

I misread your original question, you want `VARCHAR(65353)`, which MySQL can do, as long as that column size summed with the other columns in the table doesn't exceed 65535.

mysql> create table foo (str1 varchar(300), str2 varchar(300));
mysql> alter table foo modify str2 varchar(65353);
ERROR 1118 (42000): Row size too large.
The maximum row size for the used table type, not counting BLOBs, is 65535.
You have to change some columns to TEXT or BLOBs

Have you tried this?

ALTER TABLE <table_name> MODIFY <col_name> VARCHAR(65353);

This will change the **col_name**'s type to `VARCHAR(65353)`

```sql
ALTER TABLE {table_name} MODIFY [COLUMN] {column_name} {column_type} {defaults and/or not-null};
```

(Including `COLUMN` is optional.)

**Note:** *if your column was created with `NOT NULL` etc. you may need to specify those in the `MODIFY` statement to avoid losing them.*