CODE EXAMPLE FOR SQL

add column if not exists mysql

-- ALTER TABLE tbl_name ADD COLUMN column_name column_definition 
--		[FIRST|AFTER existing_column];
ALTER TABLE office ADD COLUMN phone VARCHAR(200) DEFAULT '000' AFTER name;
ALTER TABLE office ADD COLUMN flag INT(1) FIRST;
ALTER TABLE office ADD COLUMN last_col INT(2);	-- Last column is default position
-- ↓ Test it (Fiddle)