ALTER TABLE table_name ADD [COLUMN] column_name column_definition [FIRST|AFTER existing_column];
ALTER TABLE `TABLE_NAME` ADD `COLUMN_NAME` VARCHAR(50) NULL AFTER `COLUMN_NAME_AFTER`;
ALTER TABLE table ADD COLUMN column VARCHAR (255) NOT NULL AFTER column;
ALTER TABLE table_name MODIFY column_name datatype;
ALTER TABLE table ADD [COLUMN] column_name column_definition [FIRST|AFTER existing_column];
ALTER TABLE table_name ADD column_name datatype;
ALTER TABLE contacts ADD last_name varchar(40) NOT NULL AFTER contact_id, ADD first_name varchar(35) NULL AFTER last_name;
ALTER TABLE nom_table DROP nom_colonne
ALTER TABLE nom_table MODIFY nom_colonne type_donnees
add column in a table
