Three Usage Examples: Different Ways to Update SQL Statements

There are three ways to use the update statement in SQL, specific code examples are required

In SQL, the update statement is used to update data in the table. It is a very useful statement that can help us update specific data in the table or update multiple pieces of data in batches. The following will introduce three common uses of the update statement and provide specific code examples.

First usage: update a single piece of data
The most common usage is to update a record in the table. Here is an example:

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

For example, if we have a table called "students" with three columns (id, name, and age), we can use update to update the age of a certain student , the specific code is as follows:

UPDATE students
SET age = 20
WHERE id = 1;

This statement will update the age of the student with id 1 to 20.

Second usage: update multiple pieces of data
Sometimes, we need to update multiple records at once. In this case, we can use the where condition of the update statement to select the records that need to be updated. The following is an example:

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

For example, if we need to update the ages of students younger than 18 years old to 18 years old, we can use the following code:

UPDATE students
SET age = 18
WHERE age < 18;

This statement will update all ages The age for students younger than 18 years old is updated to 18 years old.

Third usage: Update a column of the data table
Sometimes, we only want to update a specific column in the table, rather than the entire record. The following is an example:

UPDATE 表名
SET 列名 = 值;

For example, if we want to update all the names in the student table to "Zhang San", we can use the following code:

UPDATE students
SET name = '张三';

This statement will update all students The names are all updated to "Zhang San".

Summary:
The update statement is an important statement in SQL used to update data in the table. In this article, we introduce three common uses of the update statement and give specific code examples. By learning these usages, we can better manage and update the data in the table.

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