1CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY, a varchar(30000), UNIQUE (a)) ENGINE=innodb; 2INSERT INTO t1 (a) VALUES (20),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL); 3SELECT * FROM t1 WHERE a BETWEEN '1' AND '100'; 4pk a 5DROP TABLE t1; 6CREATE TABLE t2 (n BLOB, UNIQUE(n)); 7INSERT INTO t2 VALUES (1); 8DELETE FROM t2 WHERE n = 1; 9DROP TABLE t2; 10