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);

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