How to delete delete in mysql

1. Introduction to deletion operation

MySQL deletion operation mainly refers to deleting data table entries in the database. Before performing the deletion operation, you must first query and locate the table item to be deleted to avoid affecting other table items. Under normal circumstances, we can complete the deletion operation through SQL statements. There are two ways to delete SQL statements: single row deletion and batch deletion.

2. Single row deletion operation

The single row deletion operation is mainly to delete a single data table record. The SQL statement format is:

DELETE FROM 表名称 WHERE 条件;

In When performing data operations, the keyword DELETE indicates the deletion operation, FROM indicates which table to delete from, and WHERE is used to determine the specific conditions for deletion. There can be multiple conditions here, and multiple conditions are connected using AND or OR.

Let’s take the example of deleting the student whose middle school number is 2021001 in the student information table:

DELETE FROM studentinfo WHERE id=2021001;

3. Batch deletion operation

The main batch deletion operation It is deleted based on multiple records that meet the conditions. The SQL statement format is:

DELETE FROM 表名称 WHERE 条件1 AND 条件2 AND ... AND 条件n;

Multiple conditions can be connected using AND or OR, where the conditions refer to the conditions that satisfy the deletion operation. Below we take the example of deleting all students who failed:

DELETE FROM studentinfo WHERE score<60;

IV. Key points of deletion operation

You need to pay attention to the following aspects when performing the MySQL deletion operation, because Each operation permanently deletes data.

1. Back up data

Before performing the deletion operation, we need to back up the data so that we can quickly restore the data if it is accidentally deleted.

2. Conditional filtering

When performing a deletion operation, it is necessary to filter according to specific conditions to avoid deleting wrong data.

3. Confirm before deletion

Before performing the deletion operation, you need to confirm the data to be deleted to ensure the accuracy of the data.

4. Transaction control

When performing a deletion operation, it is necessary to consider the combination with transaction control to ensure the consistency and integrity of the deletion operation.

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