Sql Insert Generate And Return Primary Key

21.05.202021.05.2020

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Primary Key Generation Using Oracle's Sequence

Sql Insert Generate And Return Primary Key Mean

Oracle provides the sequence utility to automatically generate unique primary keys. To use this utility to auto-generate primary keys for a CMP entity bean, you must create a sequence table and use the @AutomaticKeyGeneration annotation to point to this table.

In your Oracle database, you must create a sequence table that will create the primary keys, as shown in the following example:

This creates a sequences of primary key values, starting with 1, followed by 2, 3, and so forth. The sequence table in the example uses the default increment 1, but you can change this by specifying the increment keyword, such as increment by 3. When you do the latter, you must specify the exact same value in the cacheSize attribute of the @AutomaticKeyGeneration annotation:

SQLite autoincrement FAQ: How do I get the autoincrement value from my last SQLite INSERT command? You can get the integer value of the primary key field from the last insert into an autoincrement field using a SQLite function named lastinsertrowid, as shown in the example below. How to get the SQLite autoincrement (primary key) value after an insert. I am creating a web app in c# using a SQL Server 2005 back-end. The problem: I have a screen that is entering a record into a table and I need the primary key to follow a special format. How to get primary key value (auto-generated keys) from inserted queries using JDBC? Description: When we are inserting a record into the database table and the primary key is an auto-increment or auto-generated key, then the insert query will generate it dynamically.

If you have specified automatic table creation in the CMP bean's project settings, the sequence table will be created automatically when the entity bean is deployed. For more information, see @JarSettings Annotation. For more information on the definition of a CMP entity bean, see below.

Mar 31, 2013 Here Mudassar Ahmed Khan has explained with an example and attached sample code, how to return the value of Identity (Auto Increment) Column value after record is inserted in SQL Server database using ADO.Net with C# and VB.Net.

Primary Key Generation Using SQL Server's IDENTITY

In SQL Server you can use the IDENTITY keyword to indicate that a primary-key needs to be auto-generated. The following example shows a common scenario where the first primary key value is 1, and the increment is 1:

In the CMP entity bean definition you need to specify SQLServer(2000) as the type of automatic key generator you are using. You can also provide a cache size:

Primary Key Generation Using a Named Sequence Table

A named sequence table is similar to the Oracle sequence functionality in that a dedicated table is used to generate primary keys. However, the named sequence table approach is vendor-neutral. To auto-generate primary keys this way, create a named sequence table using the two SQL statements shown in the example:

In the CMP entity bean definition you need to specify the named sequence table as the type of automatic key generator you are using. You can also provide a cache size:

Note. When you specify a cacheSize value for a named sequence table, a series of unique values are reserved for entity bean creation. When a new cache is necessary, a second series of unique values is reserved, under the assumption that the first series of unique values was entirely used. This guarantees that primary key values are always unique, although it leaves open the possibility that primary key values are not necessarily sequential. For instance, when the first series of values is 10..20, the second series of values is 21-30, even if not all values in the first series were actually used to create entity beans.

Defining the CMP Entity Bean

When defining a CMP entity bean that uses one of the primary key generators, you use the the @AutomaticKeyGeneration annotation to point to the name of the primary key generator table to obtain primary keys. Also, you must define a primary key field of type Integer or Long to set and get the auto-generated primary key. However, the ejbCreate method does not take a primary key value as an argument. Instead the EJB container adds the correct primary key to the entity bean record.

The following example shows what the entity bean might look like. Notice that the bean uses the named sequence option described above, and that ejbCreate method does not take a primary key:

Table constraints

Synapse SQL pool supports these table constraints:

PRIMARY KEY is only supported when NONCLUSTERED and NOT ENFORCED are both used.
UNIQUE constraint is only supported with NOT ENFORCED is used.

For syntax, check ALTER TABLE and CREATE TABLE.

FOREIGN KEY constraint is not supported in Synapse SQL pool.

Remarks

Having primary key and/or unique key allows Synapse SQL pool engine to generate an optimal execution plan for a query. All values in a primary key column or a unique constraint column should be unique.

After creating a table with primary key or unique constraint in Synapse SQL pool, users need to make sure all values in those columns are unique. A violation of that may cause the query to return inaccurate result. This example shows how a query may return inaccurate result if the primary key or unique constraint column includes duplicate values.

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Examples

Sql Insert Generate And Return Primary Keys

Create a Synapse SQL pool table with a primary key:

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Create a Synapse SQL pool table with a unique constraint:

Next steps

After creating the tables for your Synapse SQL pool, the next step is to load data into the table. For a loading tutorial, see Loading data to Synapse SQL pool.

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