Assign Values to New MySQL Columns

In MySQL, you can use the ALTER TABLE statement to assign a value to a newly added column in a table. The specific steps are as follows:

1. Modify the structure of the table.

ALTER TABLE 表名 ADD 列名 数据类型;

In this case, the table name refers to the name of the table where you want to add a new column, the column name is the name of the new column to be added, and the data type is the data type of the new column.

1. – Make a new version

UPDATE 表名 SET 列名 = 值;

The table name is the name of the table to be updated, the column name is the name of the column to be updated, and the value is the value to be assigned to the new column. You can specify a specific value as needed, or use values from other columns or expressions to calculate the assignment.

Please make sure to add the new column fields before executing the UPDATE statement.

For instance, let’s say there is a table called users, which already has columns id and name. Now, we need to add a new column called age and assign values to it. This can be done by following these steps:

1. Add new column fields:

ALTER TABLE users ADD age INT;

1. Assign values to new column fields.

UPDATE users SET age = 25;

The above operation will set the age column of each row to be 25.

You can use expressions to calculate and assign values based on the values of other columns. For example, if you want to calculate the age based on the date of birth and assign it to the age column, you can use the following statement:

UPDATE users SET age = YEAR(NOW()) - YEAR(birthdate);

The statement will calculate the difference between the current year and the year in the birthdate column, then assign the result to the age column.