droP TABLE IF EXISTS t1;
CREATE TABLE t1(c1 CHAR(10) NULL UNIQUE);
INSERT INTO t1 (c1) VALUES('abc');
INSERT INTO t1 (c1) VALUES('def');
INSERT INTO t1 (c1) VALUES('abc');
ERROR 23000: Duplicate entry 'abc' for key 'c1'
SELECT * FROM t1;
c1
abc
def
DROP TABLE t1;
CREATE TABLE t1(c1 VARCHAR(10) NULL UNIQUE);
INSERT INTO t1 (c1) VALUES('abc');
INSERT INTO t1 (c1) VALUES('def');
INSERT INTO t1 (c1) VALUES('abc');
ERROR 23000: Duplicate entry 'abc' for key 'c1'
SELECT * FROM t1;
c1
abc
def
DROP TABLE t1;
CREATE TABLE t1(c1 BINARY(10) NULL UNIQUE);
INSERT INTO t1 (c1) VALUES('abc');
INSERT INTO t1 (c1) VALUES('def');
INSERT INTO t1 (c1) VALUES('abc');
ERROR 23000: Duplicate entry 'abc' for key 'c1'
SELECT * FROM t1;
c1
abc       
def       
DROP TABLE t1;
CREATE TABLE t1(c1 VARBINARY(10) NULL UNIQUE);
INSERT INTO t1 (c1) VALUES('abc');
INSERT INTO t1 (c1) VALUES('def');
INSERT INTO t1 (c1) VALUES('abc');
ERROR 23000: Duplicate entry 'abc' for key 'c1'
SELECT * FROM t1;
c1
abc
def
DROP TABLE t1;