I have an option of using a surrogate key as the pk or a column of datatype number and a column of datatype date. 1) is there a performace hit having a column of date datatype as the primary key? 2) is there a performace hit having a column of date datatype and a column of datatype number as the primary key?. If you think the data type of a primary key will have a noticeable performance improvement on your application then you must have the best designed, perfectly implemented program running on the most well tuned database with perfect statistics and most expensive speediest hardware money can buy, ever.. This oracle tutorial explains how to create, change, drop, disable, and enable a primary key in oracle with syntax and examples. in oracle, a primary key is a single field or combination of fields that uniquely defines a record..
Sometimes a column with "date" datatype needs to be part of primary key or unique key. while retrieveing result sets in a sql query, we have to use trunc(date column) for date comparision or ( selecting rows greater or less than of database field with trunc(date column)).. Update datatype of primary key without deleting the table [closed] up vote 3 down vote favorite. 3. i have created a table state which my other table, you cannot change datatypes of key fields (primary or foreign). you can't even change a datatype if the field is used in an index. so.... Oracle alter table change column datatype. you can use the oracle "alter table" syntax to change the data type for an existing column, as shown in this example: alter table table_name modify ( column_name varchar2(30)); to alter a long datatype column into a clob datatype you simply enter this ddl:.
