ALTER ADD

Add more rows to the table

ALTER TABLE table_name
ADD column_name datatype;

Adding constraints to the table

ALTER TABLE lab_location
ADD PRIMARY KEY (location_id);

this will set location_id to be primary key

Adding Foreign Key to the table

ALTER TABLE lab_location
ADD CONSTRAINT 'lab_emp_fk'
FOREIGN KEY (location_id)
REFERENCES lab_location(location_id);

Adding UNIQUE to the table

ALTER TABLE lab_location
ADD UNIQUE (location_id)

or

ALTER TABLE lab_location
ADD CONSTRAINT 'UNIQUE_location_id' UNIQUE (location_id);