Delete a table-PolarDB(PolarDB)-阿里云帮助中心

DROP TABLE removes a table and all its associated indexes, rules, triggers, and constraints from the database. Only the table owner can drop a table.

Prerequisites

Before you begin, ensure that you have:

Ownership of the table to drop

Syntax

DROP TABLE name [CASCADE | RESTRICT | CASCADE CONSTRAINTS]

Parameters

Parameter	Description
`name`	The name of the table to drop. The name can be schema-qualified.
`RESTRICT`	Refuses to drop the table if any objects depend on it. This is the default behavior.
`CASCADE`	Drops the table and removes any dependent constraints on the specified table. Other object types are not included. Dependent tables themselves are not dropped.
`CASCADE CONSTRAINTS`	Drops the table and removes any dependent constraints on the specified table. Other object types are not included.

Examples

Drop a table with no dependencies

DROP TABLE emp;

Drop a table with dependencies

If a table has dependent objects, the outcome depends on the option you specify. The following example sets up two tables where items has a foreign key referencing orders:

CREATE TABLE orders
  (order_id int PRIMARY KEY, order_date date, …);
CREATE TABLE items
  (order_id int REFERENCES orders, quantity int, …);

PolarDB behaves as follows when you drop the orders table:

DROP TABLE orders RESTRICT — PolarDB reports an error because items depends on orders.
DROP TABLE orders CASCADE — PolarDB drops orders and removes the foreign key constraint from items. The items table itself is not dropped.
DROP TABLE orders CASCADE CONSTRAINTS — PolarDB drops orders and removes the foreign key constraint from items. The items table itself is not dropped.

What's next

Create a table
Alter a table