How to write oracle delete statement

Oracle DELETE statement is used to delete records from the table. The syntax is: DELETE FROM table_name WHERE condition. Conditions are optional to restrict deletion of records. Supports cascade deletion, that is, when deleting parent table records, child table records can also be deleted. Use caution as deletion is irreversible.

Oracle DELETE Statement

The DELETE statement is used to delete records from an Oracle database table. The basic syntax is as follows:

<code>DELETE FROM table_name
WHERE condition;</code>

Where:

• table_name is the name of the table from which records are to be deleted.
• condition is optional and used to limit the records to be deleted. If condition is not specified, all records in the table will be deleted.

Example:

Delete all records in the table named "customers":

<code>DELETE FROM customers;</code>

Delete the customer_id 10 in the "customers" table Records:

<code>DELETE FROM customers
WHERE customer_id = 10;</code>

Delete records with multiple conditions:

You can use logical operators (AND, OR) to delete records that meet multiple conditions.

Example:

Delete records in the "customers" table whose city is "New York" and whose age is greater than 30:

<code>DELETE FROM customers
WHERE city = 'New York' AND age > 30;</code>

level Joint deletion:

When there are foreign key constraints between tables, deleting records in the parent table may cause records in the child table to also be deleted. This is called a cascade delete.

To enable cascading deletes, the ON DELETE CASCADE option must be specified when creating the foreign key constraint.

Example:

Consider the following table structure:

<code>CREATE TABLE orders (
  order_id NUMBER PRIMARY KEY,
  product_id NUMBER,
  CONSTRAINT FK_order_product FOREIGN KEY (product_id) REFERENCES products (product_id) ON DELETE CASCADE
);</code>

If you delete a product from the "products" table, the "orders" table will also be deleted All orders that reference this product.

Note:

• Be careful when using the DELETE statement because it is an irreversible operation. Deleted records cannot be recovered.
• Before deleting a large number of records, please use the SELECT statement to verify the deletion conditions.
• Use transaction control statements (such as COMMIT and ROLLBACK) to control changes to the database.

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