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A primary key is never null and is also unique . Example of primary key is create table emp (ecode integer NOT NULL PRIMARY KEY);
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How do you create a primay key in Oracle?
You can create a primary key column in an oracle table using the PRIMARY KEY keyword. Assuming you have an employee table that has employee information and has a column called emp_num. you can create a primary key in the table using the below command. ALTER TABLE tbl_employee_info add CONSTRAINT emp_pk PRIMARY KEY (emp_num) If you execute the above command in your database, emp_num will become the primary key of the table tbl_employee_info.
Why do you need the primary key in the database?
without you will not be able to create a relationship
How do you create an employee table with the uses of primary key?
CREATE TABLE EMPLOYEE (EMP_ID NUMBER(10) PRIMARY KEY,NAME VARCHAR2(100),EMAIL_ID VARCHAR2(50) UNIQUE);Hope it helped.SP.
What is the difference between primary key and unique index?
Primary key is a type of unique index with no null constraint on the columns involved. There can only be one Primary key whereas you can create other unique indexes on the table.
How a primary key is fixed in a sql table?
A primary key field in a sql table is created using the PRIMARY KEY keyword. ex: CREATE TABLE tbl_employee ( emp_num VARCHAR(10), emp_name VARCHAR(100), PRIMARY KEY (emp_num)) The above script creates a table called tbl_employee and sets the emp_num field as the primary key
Which field MS Access will not allow you to delete?
A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.A primary key field.
Create a macro and assign Ctrl plus l key to run this macro method?
You can record a macro and before starting the recording you can use i key as assigned key to run the macro. Also, if you have an existing macro to which you want to assign i key then Press Alt + F8 which will show you the list of existing macro. Click on Edit and type the i in the assign key box. Remember Ctrl is my default. So, if you want the macro to have Ctrl SHIFT I then turn on the caplock. Your question is not very decriptive in nature.
Is it possible to create a table without assigning a primary key if yes state the disadvantages?
Yes, it is possible to create a table without a primary key. However, not having a primary key can make it difficult to uniquely identify individual records, potentially leading to data duplication or inconsistency. It can also affect the performance of queries that rely on identifying specific rows.
What is a foreign key in Microsoft Access?
It is a field in one table that is a primary key in another table. It is used to create a relationship between two tables, normally a one to many relationship. The one side is where it is the primary key and where it is the foreign key, that is the many tables.
Can super key be as primary key?
I think super key is treated as the primary key because in a table their will be only one primary key.
Another option to launch the Microsoft Excel?
you can assign shortcut key to application by right clicking and choose properties then under shortcut key assign something you will remember
What happens if you don't assign a primary key field in Microsoft Excel?
Excel is primarily a spreadsheet, not a database, so you do not set primary keys in it. That would be something you would do in a program like Access. Setting a primary key ensures that there is a unique value in each record, meaning that record can always be uniquely identified. Without a primary key set, it is possible to end up with duplicated data and it can be harder to find data. Primary keys are also used in creating relationships, so that is more difficult to do without one.
