What is the type of the bond which is presenting the connection between two atoms TR000_1 and TR000_2?
type of bond refers to bond_type; double bond refers to bond_type = ' = '; single bond refers to bond_type = '-'; triple bond refers to bond_type = '#';
SELECT T1.bond_type FROM bond AS T1 INNER JOIN connected AS T2 ON T1.bond_id = T2.bond_id WHERE T2.atom_id = 'TR000_1' AND T2.atom_id2 = 'TR000_2'