ALTER VARIABLE¶

Modifies the properties of an existing schema variable.

See also:: CREATE VARIABLE , DROP VARIABLE , SHOW SCHEMA VARIABLES IN SCHEMA , DESCRIBE VARIABLE

Syntax¶

ALTER VARIABLE [ IF EXISTS ] <name> RENAME TO <new_name>

ALTER VARIABLE [ IF EXISTS ] <name> SET DEFAULT <default_value>

ALTER VARIABLE [ IF EXISTS ] <name> DROP DEFAULT

ALTER VARIABLE [ IF EXISTS ] <name> SET COMMENT = '<string_literal>'

ALTER VARIABLE [ IF EXISTS ] <name> UNSET COMMENT

Parameters¶

name

Specifies the identifier for the variable to alter. The identifier can be qualified with the schema name or with both the database and schema names.

RENAME TO new_name

Specifies the new identifier for the variable; must be unique within the schema.

You can move the object to a different database and/or schema while optionally renaming the object. To do so, specify a qualified new_name value that includes the new database and/or schema name in the form db_name.schema_name.object_name or schema_name.object_name, respectively.

Note

The destination database and/or schema must already exist. In addition, an object with the same name cannot already exist in the new location; otherwise, the statement returns an error.
Moving an object to a managed access schema is prohibited unless the object owner (that is, the role that has the OWNERSHIP privilege on the object) also owns the target schema.

When a variable is renamed, any session variables that shadow it are unaffected because session variables and schema variables are resolved by name independently.

SET DEFAULT default_value

Changes the default value for the variable. The expression is evaluated at statement execution time and must be compatible with the variable’s declared data type. To reset a variable’s current value to the new default, use SET schema.name = DEFAULT.

DROP DEFAULT

Removes the default value from the variable. The variable’s current value is unchanged; only the stored default is cleared.

SET COMMENT = 'string_literal'

Sets or replaces the comment for the variable.

UNSET COMMENT

Removes the comment from the variable.

Access control requirements¶

A role used to execute this operation must have the following privileges at a minimum:

Privilege	Object	Notes
OWNERSHIP	Variable	OWNERSHIP is a special privilege on an object that is automatically granted to the role that created the object, but can also be transferred using the GRANT OWNERSHIP command to a different role by the owning role (or any role with the MANAGE GRANTS privilege). Note that in a managed access schema, only the schema owner (i.e. the role with the OWNERSHIP privilege on the schema) or a role with the MANAGE GRANTS privilege can grant or revoke privileges on objects in the schema, including future grants.

For instructions on creating a custom role with a specified set of privileges, see Creating custom roles.

For general information about roles and privilege grants for performing SQL actions on securable objects, see Overview of Access Control.

Usage notes¶

The IF EXISTS modifier suppresses the error if the variable doesn’t exist. The statement succeeds silently in that case.
Only metadata properties can be changed with ALTER VARIABLE. To change a variable’s current value, use SET with a qualified name.
The data type of a variable can’t be changed after creation. Drop and re-create the variable to change its type.
Regarding metadata:

Attention

Customers should ensure that no personal data (other than for a User object), sensitive data, export-controlled data, or other regulated data is entered as metadata when using the Snowflake service. For more information, see Metadata fields in Snowflake.

Examples¶

Rename a variable:

ALTER VARIABLE myschema.tax_rate RENAME TO myschema.regional_tax_rate;

Update the default value:

ALTER VARIABLE myschema.tax_rate SET DEFAULT 0.10;

Add a comment:

ALTER VARIABLE myschema.tax_rate
  SET COMMENT = 'Regional tax rate, updated annually by finance';

Remove the default value:

ALTER VARIABLE myschema.batch_cursor DROP DEFAULT;