How to update and delete data in MySQL using SQL statements?

How to update and delete data in MySQL using SQL statements?

In the MySQL database, updating and deleting data are very common operations. By using SQL statements, we can easily update and delete data in the table. This article will introduce how to use SQL statements to update and delete data in MySQL, and provide specific code examples.

Update data

In MySQL, we use the UPDATE statement to update data in the table. The basic syntax of the update statement is as follows:

UPDATE 表名
SET 列名1=新值1, 列名2=新值2, ...
WHERE 条件;

Among them, table name is the name of the table to update the data, column name 1=new value 1, column name 2=new value 2, ... indicates the column to be updated and the corresponding new value. The WHERE clause is optional and is used to specify the conditions for updating data.

The following is a specific example:

Suppose we have a table named students, containing the following fields: id, name, age, grade. Now we want to update student Zhang San’s age to 18 years old and grade A. We can execute the following SQL statement:

UPDATE students
SET age=18, grade='A'
WHERE name='张三';

This statement will update the name Zhang San in the students table the age and grades of students.

Delete data

In MySQL, we use the DELETE statement to delete data in the table. The basic syntax of the delete statement is as follows:

DELETE FROM 表名
WHERE 条件;

Among them, table name is the name of the table to delete data, and the WHERE clause is used to specify the conditions for deleting data.

The following is a specific example:

Suppose we have a table named students, containing the following fields: id, name, age, grade. Now we want to delete students who are younger than 18 years old. We can execute the following SQL statement:

DELETE FROM students
WHERE age < 18;

This statement will delete students who are younger than 18 years old in the students table.

Summary

By using SQL statements, we can easily update and delete data in MySQL. When updating data, use the UPDATE statement and specify the columns to be updated and the corresponding new values. You can also use the WHERE clause to specify the conditions for updating the data. When deleting data, use the DELETE statement and use the WHERE clause to specify the conditions for deleting data. These operations can help us better manage and maintain the data in the database.

The above is an introduction and code examples on how to use SQL statements to update and delete data in MySQL. Hope this article can be helpful to you!

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