SQL unique varchar case sensitivity question

Seth picture Seth · Jun 23, 2011 · Viewed 49.8k times · Source

I'm trying to populate a SQL table with a list of words. The table itself it pretty simple:

CREATE TABLE WORDS(
  ID BIGINT AUTO_INCREMENT, 
  WORD VARCHAR(128) NOT NULL UNIQUE, 
  PRIMARY KEY(ID)
);

The problem I'm running into is this: when I do the following inserts back to back

INSERT INTO WORDS(WORD) VALUES('Seth');
INSERT INTO WORDS(WORD) VALUES('seth');

The second insert fails with a constraint violation ("Duplicate entry 'seth' for key 'WORD'").

How can I get the UNIQUE constraint on WORD to be case sensitive?

Answer

Bill Brasky picture Bill Brasky · Jun 23, 2011

Looks like mysql is case insensitive by default:

You probably need to create the column with a case sensitive collation (e.g. utf8_bin):

CREATE TABLE WORDS (
    ID BIGINT AUTO_INCREMENT, 
    WORD VARCHAR(128) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL UNIQUE, 
    PRIMARY KEY(ID)
);