Cratedb Generated Column Primary Key

Jul 21, 2013 I am trying to make my computed column (QuoteID) the primary key. QuoteID is a concatenation of two fields as you can see below. Below is how SQL Server 2008 scripts the CREATE TABLE without QuoteID being the primary key. For some reason, I'm able to set QuoteID as the primary key in the. Try this create instead - you are not declaring your. Insert from dynamic queries constraints ¶. In some cases SELECT statements produce invalid data. This opens a rare occasion for inconsistent outcomes. If the select statement produces data where a few rows contain invalid column names, or where you have rows which types are not compatible among themselves, some rows will be inserted while others will fail.

This means that if I were to make a primary key, it would need to comprise all columns. Queries against the table will almost always be to pull back a single record, i.e. All columns will be filtered in the query. Since every column will need to be searched, does having a primary key benefit me at all (besides enforcing uniqueness of records)? Jul 21, 2013 I am trying to make my computed column (QuoteID) the primary key. QuoteID is a concatenation of two fields as you can see below. Below is how SQL Server 2008 scripts the CREATE TABLE without QuoteID being the primary key. For some reason, I'm able to set QuoteID as the primary key in the. Try this create instead - you are not declaring your.

Primary Key Generation Using Oracle's Sequence

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:

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.

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:

Cratedb Generated Column Primary Keyboard

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: Ascii armored pgp public key generator.

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

Cratedb Generated Column Primary Key Definition

method does not take a primary key:

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