MySQL: CREATE TABLE, BLOB, UNIQUE, INDEX etc

My code: $query=" CREATE TABLE IF NOT EXISTS temp3 UNIQUE(CON175) IGNORE SELECT DISTINCT CONCAT($tbl2.this,$tbl2.that) AS CON175 FROM $tbl2 WHERE $tbl2.this='$rcc' "; gives error: Query failed: BLOB column 'CON175' used in key specification without a key length. Manual suggests to give a BLOB a length: CREATE TABLE test (blob_col BLOB, INDEX(blob_col(10))); ...but how do you work this into the above query? CREATE TABLE IF NOT EXISTS temp3 (UNIQUE(CON175) BLOB, INDEX(CON175)(50))... ..does not work, I suppose because CON175 has not been created yet? CON175 is BLOB by default resulting from this part of the query: IGNORE SELECT DISTINCT CONCAT($tbl2.this,$tbl2.that)... this and that are varchar types. How do I set this as varchar instead: UNIQUE(CON175) VARCHAR(50) does not work. http://www.mysql.com/doc/en/CREATE_TABLE.html - lacks examples! John                                            http://www.cantor.com CONFIDENTIAL: This e-mail, including its contents and attachments, if any, are confidential. If you are not the named recipient please notify the sender and immediately delete it. You may not disseminate, distribute, or forward this e-mail message or disclose its contents to anybody else. Copyright and any other intellectual property rights in its contents are the sole property of Cantor Fitzgerald. E-mail transmission cannot be guaranteed to be secure or error-free. The sender therefore does not accept liability for any errors or omissions in the contents of this message which arise as a result of e-mail transmission. If verification is required please request a hard-copy version. Although we routinely screen for viruses, addressees should check this e-mail and any attachments for viruses. We make no representation or warranty as to the absence of viruses in this e-mail or any attachments. Please note that to ensure regulatory compliance and for the protection of our customers and business, we may monitor and read e-mails sent to and from our server(s). For further important information, please read the Important Legal Information and Legal Statement at http://www.cantor.com/legal_information.html