• Create Table With Auto Generated Primary Key Db2 Download
• Create Table With Auto Generated Primary Key Db2 Version
• Create Table With Primary Key In Db2 Example
• Db2 Create Table Primary Key Autoincrement

When creating a table in which you must uniquely identify each row that will be added to the table, you can add an identity column to the table. To guarantee a unique numeric value for each row that is added to a table, you should define a unique index on the identity column or declare it a primary key.

1. Create table orders (orderno smallint not null generated always as identity (start with 500 increment by 1 cycle), shippedto varchar (36), orderdate date) This column is defined with a starting value of 500, incremented by 1 for every new row inserted, and will recycle when the maximum value is reached.
2. AUTOINCREMENT option allows you to automatically generate unique integer numbers (IDs, identity, sequence) for a column. Quick Example: - Define a table with an auto-increment column (id starts at 100) CREATE TABLE airlines ( id INT AUTOINCREMENT PRIMARY KEY, name VARCHAR(90) ) AUTOINCREMENT = 100; - Insert a row, ID will be automatically generated INSERT INTO airlines.

Summary: in this tutorial, you will learn how to use DB2 identity column to define an identity column for a table.

Introduction to Db2 identity column

When you create a new table and use the GENERATED AS IDENTITY option for a column, this column will become an identity column.

An identity column contains a unique integer for each row in the table. When you insert a new row into the table, Db2 automatically generates a sequential integer for the identity column. Thus, identity columns are ideal for the primary key columns such as book id (book_id) or publisher id (publisher_id).

The following shows the syntax of declaring an identity column:

In this syntax:

First, specify the data type for the identity column. The data type can be SMALLINT, INT, and BIGINT.

Create Table With Auto Generated Primary Key Db2 Download

Second, use either GENERATED ALWAYS or GENERATED BY DEFAULT option.

• For the GENERATED ALWAYS option, Db2 will always generate a sequential integer for the identity column. Any attempt to insert a value into the identity column with GENERATED ALWAYS option will result in an error.
• On the other hand, for the GENERATED BY DEFAULT option, DB2 will only generate the sequential integer when you don’t provide the value for the identity column. If you insert a value into the identity column with the GENERATED BY DEFAULT option, Db2 will use your value instead of using the system generated one.

Third, specify the identity column’s options:

The identity option allows you to specify the starting value in START WITH clause and increment value in the INCREMENT BY.

If the increment value is positive, you will have an ascending sequence like 1, 2, 3, … In case it is negative, then you will have a descending sequence e.g., -1, -2, -3, …

The MINVALUE and MAXVALUE options allow you to specify the minimum and maximum values that Db2 will generate.

The CYCLE or NOCYCLE Php how execute artisan key generate. option determines whether Db2 should restart the values when it has generated all the possible values.

For example, if you use CYCLE option and the sequence is 1, 2, 3, then Db2 will return 1 if it has generated 3. However, if you use the NO CYCLE option, Db2 will raise an error instead.

Notice that a table can have one and only one identity column in a table in Db2.

Db2 identity column examples

Let’s take some examples of using identity columns to get a better understanding.

1) Db2 identity column example

First, create a new table named t1 with the id column as an identity column.

The value of the id column will start with 10 and increment by 10.

Second, use the following INSERT statement to insert three rows into the t1 table:

Create Table With Auto Generated Primary Key Db2 Version

Third, view data from the t1 table using the following SELECT statement:

Here is the output:

2) Db2 identity column with CYCLE example

First, create a new table named t2 whose id column is an identity column.

Create Table With Primary Key In Db2 Example

Second, insert seven rows into the t2 table:

Db2 Create Table Primary Key Autoincrement

Third, query data from the t2 table:

Here is the output:

/call-of-duty-2-key-generator.html. In this example, the id column’s value starts with -1 and has an increment of one.

Because the MAXVALUE is 2 and CYCLE option is specified, the sequence is -1, 0, 1 ,2, -1, 0, 1 …

In this tutorial, you have learned how to use the Db2 identity column to define an identity column for a table.