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This article mainly introduces how to write the mysql deletion sentence, which is very detailed and has a certain reference value. Friends who are interested must finish it!

The mysql delete statement is "DROP DATABASE [IF EXISTS] database name", which deletes all tables in the database and deletes the database at the same time; where the keyword "IF EXISTS" is optional and, if set to prevent errors when the database does not exist.

The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.

In mysql, deleting a database means that all data and associated objects in the database are permanently deleted and cannot be undone. Therefore, it is important to execute this query with additional considerations. To delete a database, use the DROP DATABASE statement, as follows:

DROP DATABASE [IF EXISTS] database name

The syntax is as follows:

Database name: specifies the name of the database to delete.

IF EXISTS: optional section to prevent errors when the database does not exist.

DROP DATABASE: delete all tables in the database and delete the database at the same time. Be very careful when using this statement to avoid erroneous deletion. If you want to use DROP DATABASE, you need to obtain database DROP permission.

If you want to practice using DROP DATABASE statements, you can create a new database and then delete it. Take a look at the following query:

CREATE DATABASE IF NOT EXISTS tempdb;SHOW DATABASES;DROP DATABASE IF EXISTS tempdb

The three statements are described as follows:

First, a database named tempdb is created using the CREATE DATABASE statement.

Second, use the SHOW DATABASES statement to display all databases.

Third, the database named tempdb is deleted using the DROP DATABASE statement.

If there is no test_db_del database, and you use the command to delete the database from the database list, the system will report an error, as shown below:

Mysql > DROP DATABASE test_db_del;ERROR 1008 (HY000): Can't drop database 'test_db_del'; database doesn't exist

If you use the IF EXISTS clause, you can prevent the system from reporting such errors, as follows:

Mysql > DROP DATABASE IF EXISTS test_db_del;Query OK, 0 rows affected, 1 warning (0.00 sec)

Be very careful when using the DROP DATABASE command, and MySQL will not give you any confirmation after executing the command. After DROP DATABASE deletes the database, all tables and data stored in the database are also deleted and cannot be recovered. Therefore, it is best to back up the database before deleting it.

The above is all the contents of this article "how to write mysql deletion sentences". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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