Answers for "alter table add"

append column sql

ALTER TABLE table_name
ADD column_name datatype;

--example
ALTER TABLE Customers
ADD Email varchar(255);

sql server alter column

ALTER TABLE table_name 
ALTER COLUMN column_name new_data_type(size);

alter table add column

ALTER TABLE table
ADD COLUMN column VARCHAR (255) NOT NULL AFTER column;

rename column sql

ALTER TABLE nom_table
RENAME COLUMN colonne_ancien_nom TO colonne_nouveau_nom