当前位置:Gxlcms > 数据库问题 > ORACLE_DELETE

ORACLE_DELETE

时间:2021-07-01 10:21:17 帮助过:4人阅读


The SQL DELETE Statement

The DELETE statement is used to delete existing records in a table.

DELETE Syntax

DELETE FROM table_name
WHERE condition;

Note: Be careful when deleting records in a table! Notice the WHERE clause in the DELETE statement. The WHERE clause specifies which record(s) that should be deleted. If you omit the WHERE clause, all records in the table will be deleted!


Demo Database

Below is a selection from the "Customers" table in the Northwind sample database:

CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
1

Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbk?p Christina Berglund Berguvsv?gen 8 Lule? S-958 22 Sweden

 

SQL DELETE Example

The following SQL statement deletes the customer "Alfreds Futterkiste" from the "Customers" table:

Example

DELETE FROM Customers
WHERE CustomerName=‘Alfreds Futterkiste‘;

The "Customers" table will now look like this:

CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbk?p Christina Berglund Berguvsv?gen 8 Lule? S-958 22 Sweden

Delete All Records

It is possible to delete all rows in a table without deleting the table. This means that the table structure, attributes, and indexes will be intact:

DELETE FROM table_name;

or:

DELETE * FROM table_name;

Delete All Null Records

delete * from emp where comm is null;

delect *  from emp where comm=‘‘; 

CREATE OR REPLACE PROCEDURE emp01_delete_null AS
BEGIN
       DELETE  FROM emp01 WHERE comm IS NULL;
       COMMIT;
END emp01_delete_null;

execute emp01_delete_null;

 

ORACLE_DELETE

标签:replace   proc   when   int   maria   str   har   sam   ons   

人气教程排行