DROP TABLE IF EXISTS t1; CREATE TABLE t1(c1 CHAR(10) NOT NULL PRIMARY KEY); 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 'PRIMARY' SELECT * FROM t1; c1 abc def DROP TABLE t1; CREATE TABLE t1(c1 VARCHAR(10) NOT NULL PRIMARY KEY); 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 'PRIMARY' SELECT * FROM t1; c1 abc def DROP TABLE t1; CREATE TABLE t1(c1 BINARY(10) NOT NULL PRIMARY KEY); 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 'PRIMARY' SELECT * FROM t1; c1 abc def DROP TABLE t1; CREATE TABLE t1(c1 VARBINARY(10) NOT NULL PRIMARY KEY); 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 'PRIMARY' SELECT * FROM t1; c1 abc def DROP TABLE t1;