It's a very valid issue from developers that are not sql developers or sql DBA's and don't spend all their time in sql. Even in pure sql I'd rather have a meaningless auto-generated key as the primary key when joining than have to remember to pass n bits of data around being the...
MySQL / SQL Server / Oracle / MS Access: CREATETABLEPersons ( ID intNOTNULL, LastName varchar(255)NOTNULL, FirstName varchar(255), Age int, CONSTRAINTPK_PersonPRIMARYKEY(ID,LastName) ); Note:In the example above there is only ONEPRIMARY KEY(PK_Person). However, the VALUE of the prim...
So i think while updating ur inserting a value which exists in this column.plz go through this-http://www.w3schools.com/sql/sql_primarykey.aspHope it helpsthanx and regardsTuesday, October 26, 2010 11:54 AMhi can you write your update statement ...
How Can I solve this problem ? ASk Doctor DoctorID - primary key UMUser UserID - primary key DoctorID - foreign key relationship to Doctor DoctorID primary key http://www.w3schools.com/sql/sql_foreignkey.asp
You did not include a value in the insert statement the value forlogin.PRIMARYcolumn which happens...
You did not include a value in the insert statement the value forlogin.PRIMARYcolumn which happens...
if (!mysql_query($sql,$con)) { die('Error: ' . mysql_error()); } mysql_close($con); ?> I am trying to submit data to my database via a form and when I click Submit, I get: Duplicate entry '' for key 1 I understand that it means I have a duplicate entry with the ID ...
A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields). PRIMARY KEY on CREATE TABLE The following SQL creates aPRIMARY KEYon the "ID" column when the "Persons" table is created: ...