### Database Schema:
CREATE TABLE connected (
	atom_id	TEXT	NOT NULL	PRIMARY KEY,
	atom_id2	TEXT	NOT NULL	PRIMARY KEY,
	bond_id	TEXT	NULL	DEFAULT NULL,
	foreign key (atom_id2) references atom (atom_id),
	foreign key (atom_id) references atom (atom_id),
	foreign key (bond_id) references bond (bond_id)
);

CREATE TABLE atom (
	atom_id	TEXT	NOT NULL	PRIMARY KEY,
	molecule_id	TEXT	NULL	DEFAULT NULL,
	element	TEXT	NULL	DEFAULT NULL,
	foreign key (molecule_id) references molecule (molecule_id)
);

CREATE TABLE bond (
	bond_id	TEXT	NOT NULL	PRIMARY KEY,
	molecule_id	TEXT	NULL	DEFAULT NULL,
	bond_type	TEXT	NULL	DEFAULT NULL,
	foreign key (molecule_id) references molecule (molecule_id)
);

CREATE TABLE molecule (
	molecule_id	TEXT	NOT NULL	PRIMARY KEY,
	label	TEXT	NULL	DEFAULT NULL
);

### User's Query:
How many atoms with iodine and with sulfur type elements are there in single bond molecules?

### Extra Knowledge:
with iodine element refer to element = 'i'; with sulfur element refers to element = 's'; single type bond refers to bond_type = '-'; Should consider the distinct atoms when counting;
SELECT COUNT(DISTINCT CASE WHEN T1.element = 'i' THEN T1.atom_id ELSE NULL END) AS iodine_nums , COUNT(DISTINCT CASE WHEN T1.element = 's' THEN T1.atom_id ELSE NULL END) AS sulfur_nums FROM atom AS T1 INNER JOIN connected AS T2 ON T1.atom_id = T2.atom_id INNER JOIN bond AS T3 ON T2.bond_id = T3.bond_id WHERE T3.bond_type = '-'