PK Field Not Null Is Being Null
I m newbie. I made a MySQL database table and in the primary key field I set the data type VAR CHAR.I also set it not null .BUT still I can insert blank values in this PRIMARY KEY field. If I just blank my primary key field by this query- Insert Tablename Values ('','','','','',''); (if my table has 6 fields).HOW IS IT POSSIBLE. How can PK field allow blank value when I set not null. HOW TO SOLVE IT.
2. I use a MySQL GUI Tools from http://dev.mysql.com/downloads/. In Table viewer of Query browser, each time I insert the first field, it sets the datatype to INTEGER,NOT NULL, AUTO INCREMENT. But I change it to VARCHAR as needed. Do I have to/should use Integer type in PK field and can Varchar be incremented.
3.Can I set user privilege to a particular row (on a particular PK); HOW?
4. Is it correct/incorrect that the name of the foreign key has to be the same as the name of the corresponding PK. I saw that in MySQL I can easily change the FK name to anything else and then just make a reference of FK to the PK.
5. How can I make a one-to-one relationship in MySQL;
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