CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY, a varchar(30000), UNIQUE (a)) ENGINE=innodb;
INSERT INTO t1 (a) VALUES (20),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL);
SELECT * FROM t1 WHERE a BETWEEN '1' AND '100';
pk	a
DROP TABLE t1;
CREATE TABLE t2 (n BLOB, UNIQUE(n));
INSERT INTO t2 VALUES (1);
DELETE FROM t2 WHERE n = 1;
DROP TABLE t2;