Mirror of <https://developer.salesforce.com/docs/data/data-cloud-query-guide/references/dc-sql-reference/alter-table.html> (Salesforce, Data 360 Query Guide), read 2026-10-23. Salesforce's own page is the authority; this copy exists because that site refuses non-browser readers.

ALTER TABLE

Applies to: ❌ Data 360 SQL ✅ Tableau Hyper API

Change the definition of a table.

where column_constraint is:

and table_constraint is as described in CREATE TABLE.

ALTER TABLE changes the definition of an existing table. Hyper currently only supports the following changes:

RENAME The RENAME forms change the name of a table, the name of an individual column in a table, or the name of a constraint of the table. There is no effect on the stored data.

ADD COLUMN [ IF NOT EXISTS ] This form adds a new column to the table, using the same syntax as CREATE TABLE. If IF NOT EXISTS is specified and a column already exists with this name, no error is thrown. In contrast to CREATE TABLE, which supports any variable-free expression, including non-constant expressions like random(), the default value here must be a constant.

DROP COLUMN [ IF EXISTS ] This form drops a column from a table. Columns with indexes and table constraints can't be dropped.

ADD table_constraint [ NOT VALID ] This form adds a new constraint to a table using the same syntax as CREATE TABLE.

Some forms of ALTER TABLE that act on a single table can be combined into a list of multiple alterations to be applied together. It is possible to add several columns and/or drop several columns in a single command. It is also possible to create multiple column constraints in a single command. It is not possible to combine altering columns with adding constraints.

IF EXISTS Do not throw an error if the table does not exist.

<name> The name (optionally schema-qualified) of an existing table to alter.

<column_name> Name of a new or existing column.

<new_column_name> New name for an existing column.

<new_name> New name for the table.

<data_type> Data type of the new column.

The key word COLUMN is noise and can be omitted.

Changing any part of a system catalog table is not permitted.

To add a column of type text to a table:

To drop a column from a table:

To rename an existing column:

To rename an existing table:

To add an unnamed assumed foreign key constraint to a table:

See CREATE TABLE for more examples of table constraints.