-- echo initialization
CREATE TABLE unique_table(id int, col1 int, col2 int);
INSERT INTO unique_table VALUES (1,1,1);

-- echo 1. unique test
CREATE UNIQUE INDEX index_id on unique_table(id);
INSERT INTO unique_table VALUES (2,1,1);
CREATE UNIQUE INDEX index_id on unique_table(id);
INSERT INTO unique_table VALUES (3,2,1);
INSERT INTO unique_table VALUES (1,2,1);

-- echo 2. select
-- sort SELECT * FROM unique_table;