Alter a table column

Use the ALTER TABLE command to add new columns, drop non-primary key columns, or rename a primary key column.

To change the table settings, see Altering table properties.

Add a column

Add an age column of type int to the table cycling.cyclist_alt_stats.

ALTER TABLE cycling.cyclist_alt_stats ADD cyclist_age int;

The ALTER TABLE command creates the column metadata, adds the column to the table schema, and sets the value to null for all rows.

Verify that a column is added

Verify that the column was added with null values.

SELECT id, cyclist_age AS age FROM cycling.cyclist_alt_stats LIMIT 3;
Results

The result set shows the first three rows.

Rename a column

Rename the id primary key column to cyclist_id.

ALTER TABLE cycling.cyclist_alt_stats RENAME id TO cyclist_id;

Restriction: Only primary key columns can be renamed.

Add a collection column

Alter the table cycling.upcoming_calendar to add a map named description to store a name and description for each race.

ALTER TABLE cycling.upcoming_calendar 
  ADD description map<text,text>;

Verify the collection column

Verify the results:

SELECT * FROM cycling.upcoming_calendar WHERE year = 2015 AND month = 6;
Results

Map type columns display in a JSON format.

See also:

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