Check out example codes for "mysql add columns". It will help you in understanding the concepts better.
Code Example 1
ALTER TABLE table
ADD [COLUMN] column_name_1 column_1_definition [FIRST|AFTER existing_column],
ADD [COLUMN] column_name_2 column_2_definition [FIRST|AFTER existing_column],
...
;
Code Example 2
ALTER TABLE table_name
ADD [COLUMN] column_name column_definition [FIRST|AFTER existing_column];
Code Example 3
ALTER TABLE Table_name ADD name_column INT(255);
Learn ReactJs, React Native from akashmittal.com