• Primary keys are unique and not nullable.
• Primary key definition(s) from databases.about.com∞ and techonthenet.com∞. In short, each row in a table must have a unique identifier for that row. That identifier (the primary key) is often a single column, but may consist of multiple columns.
• Primary Key Values should not change. Some SQL engines support RI (Referential Integrity) rules with cascading updates. While this feature will allow for the changing of a primary key value, it is generally a bad idea to plan on editing a Primary Key Value. If you are sure the value of a Primary Key will never change, you can use this column value (Social Number). If you are not sure, use a internal counted number as the primary key and define the changeable value column as a unique constraint (product number).
  
  Deletions:
  - Use one and only one primary key for each file.
• Primary keys are unique.
• Primary key definition(s) from databases.about.com∞ and techonthenet.com∞. In short, each record in a table must have a unique identifier for that record. That identifier (the primary key) is often a single column, but may consist of multiple columns.
• Primary Key Values should not change. Some SQL engines support RI (Referential Integrity) rules with cascading updates. While this feature will allow for the changing of a primary key value, it is generally a bad idea to plan on editing a Primary Key Value. If you are sure the value of a Primary Key will never change, you can use this field value (Social Number). If you are not sure, use a internal counted number and define the changeable value field as a secondary key (product number).
  
  

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  Edited on 2005-07-14 01:31:35 by NorbertGutscher
  
  Deletions:
  

  Sub-Sub Heading

For Pervasive ODBC compliance

For xxx ODBC compliance

• Primary Key Values should not change. Some SQL engines support RI (Referential Integrity) rules with cascading updates. While this feature will allow for the changing of a primary key value, it is generally a bad idea to plan on editing a Primary Key Value. If you are sure the value of a Primary Key never change, you can use this field value (Social Number). If you are not sure, use a intern counted number and define the changeable value field as a secondary key (product number).

For Pervasive ODBC compilance

For xxx ODBC compilance

• Primary keys are unique.
• Primary key definition(s) from databases.about.com∞ and techonthenet.com∞. In short, each record in a table must have a unique identifier for that record. That identifier (the primary key) is often a single column, but may consist of multiple columns.
• When the primary key of one table is stored in another table for the purpose of creating a relationship between those two tables, it is referred to as a Foreign Key.
• Primary Key Values should not change. Some SQL engines support RI (Referential Integrity) rules with cascading updates. While this feature will allow for the changing of a primary key value, it is generally a bad idea to plan on editing a Primary Key Value.
  
  Deletions:
  - Use one and only one primary unique key for each file
  
  

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  Edited on 2005-07-05 09:53:25 by AlanB
  
  Additions:
  please edit, correct and complete this page...
  
  Deletions:
  please edit, correct and compleate this page...
  
  

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  Edited on 2005-07-01 15:21:43 by NorbertGutscher [first steps]
  
  Additions:
  please edit, correct and compleate this page...

First

• Use one and only one primary unique key for each file

• Alpha maximum 255 bytes
• Date as YYMD Date
• Time as HMSH Time
  
  Deletions:
  

  Index

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