DROP TABLE¶

Removes a table from the current or specified schema, but retains a version of the table so that it can be recovered by using UNDROP TABLE. For information, see Usage Notes.

See also:

CREATE TABLE , ALTER TABLE , SHOW TABLES , TRUNCATE TABLE , DESCRIBE TABLE

Syntax¶

DROP TABLE [ IF EXISTS ] <name> [ CASCADE | RESTRICT ]
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Parameters¶

name

Specifies the identifier for the table to drop. If the identifier contains spaces, special characters, or mixed-case characters, the entire string must be enclosed in double quotes. Identifiers enclosed in double quotes are also case-sensitive (for example, "My Object").

If the table identifier is not fully-qualified (in the form of db_name.schema_name.table_name or schema_name.table_name), the command looks for the table in the current schema for the session.

CASCADE | RESTRICT

Specifies whether the table can be dropped if foreign keys exist that reference the table:

  • CASCADE: Drops the table even if the table has primary or unique keys that are referenced by foreign keys in other tables.

  • RESTRICT: Returns a warning about existing foreign key references and doesn’t drop the table.

Default: CASCADE for standard tables; RESTRICT for hybrid tables. See also Dropping hybrid tables.

Access control requirements¶

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

Privilege

Object

Notes

OWNERSHIP

Table

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).

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¶

  • Dropping a table does not permanently remove it from the system. A version of the dropped table is retained in Time Travel for the number of days specified by the data retention period for the table:

    • Within the Time Travel retention period, you can restore a dropped table by using the UNDROP TABLE command.

    • Changing the Time Travel retention period for the account or for a parent object (a database or a schema) after you drop a table doesn’t change the Time Travel retention period for the dropped table. For more information, see the note in the Time Travel topic.

    • When the Time Travel retention period ends, the next state for the dropped table depends on whether it is permanent, transient, or temporary:

      • A permanent table moves into Fail-safe. In Fail-safe (7 days), a dropped table can be recovered, but only by Snowflake. When the table leaves Fail-safe, it is purged.

      • A transient or temporary table has no Fail-safe, so it is purged when it moves out of Time Travel.

        Note

        A long-running Time Travel query delays the movement of any data and objects (tables, schemas, and databases) in the account into Fail-safe, until the query completes. The purging of temporary and transient tables is delayed in the same way.

      • After a dropped table is purged, it can’t be recovered; it must be recreated.

  • After you drop a table, creating a table with the same name creates a new version of the table. You can still restore the dropped version of the previous table by following these steps:

    1. Rename the current version of the table.

    2. Use the UNDROP TABLE command to restore the previous version of the table.

  • Before dropping a table, verify that no views reference the table. Dropping a table referenced by a view invalidates the view (that is, querying the view returns an “object does not exist” error).

  • To drop a table, you must use a role that has OWNERSHIP privilege on the table.

  • When the IF EXISTS clause is specified and the target object doesn’t exist, the command completes successfully without returning an error.

Dropping hybrid tables¶

When you drop a hybrid table without specifying the RESTRICT or CASCADE option, and the hybrid table has a primary-key/foreign-key or unique-key/foreign-key relationship with another table, the DROP TABLE command fails with an error. The default behavior is RESTRICT.

For example:

CREATE OR REPLACE HYBRID TABLE ht1(
  col1 NUMBER(38,0) NOT NULL,
  col2 NUMBER(38,0) NOT NULL,
  CONSTRAINT pkey_ht1 PRIMARY KEY (col1, col2));

CREATE OR REPLACE HYBRID TABLE ht2(
  cola NUMBER(38,0) NOT NULL,
  colb NUMBER(38,0) NOT NULL,
  colc NUMBER(38,0) NOT NULL,
  CONSTRAINT pkey_ht2 PRIMARY KEY (cola),
  CONSTRAINT fkey_ht1 FOREIGN KEY (colb, colc) REFERENCES ht1(col1,col2));

DROP TABLE ht1;
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SQL compilation error:
Cannot drop the table because of dependencies

The DROP TABLE command fails in this case. If necessary, you can override the default behavior by specifying CASCADE in the DROP TABLE command.

DROP TABLE ht1 CASCADE;
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Alternatively in this case, you could drop the dependent table ht2 first, then drop table ht1.

Examples¶

Drop a table:

SHOW TABLES LIKE 't2%';

+---------------------------------+------+---------------+-------------+-----------+------------+------------+------+-------+--------------+----------------+
| created_on                      | name | database_name | schema_name | kind      | comment    | cluster_by | rows | bytes | owner        | retention_time |
|---------------------------------+------+---------------+-------------+-----------+------------+------------+------+-------+--------------+----------------+
| Tue, 17 Mar 2015 16:48:16 -0700 | T2   | TESTDB        | PUBLIC      | TABLE     |            |            |    5 | 4096  | PUBLIC       |              1 |
+---------------------------------+------+---------------+-------------+-----------+------------+------------+------+-------+--------------+----------------+

DROP TABLE t2;

+--------------------------+
| status                   |
|--------------------------|
| T2 successfully dropped. |
+--------------------------+

SHOW TABLES LIKE 't2%';

+------------+------+---------------+-------------+------+---------+------------+------+-------+-------+----------------+
| created_on | name | database_name | schema_name | kind | comment | cluster_by | rows | bytes | owner | retention_time |
|------------+------+---------------+-------------+------+---------+------------+------+-------+-------+----------------|
+------------+------+---------------+-------------+------+---------+------------+------+-------+-------+----------------+
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Drop the table again, but don’t raise an error if the table does not exist:

DROP TABLE IF EXISTS t2;

+------------------------------------------------------------+
| status                                                     |
|------------------------------------------------------------|
| Drop statement executed successfully (T2 already dropped). |
+------------------------------------------------------------+
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