Package org.hibernate.dialect.unique

Class SkipNullableUniqueDelegate

java.lang.Object

org.hibernate.dialect.unique.AlterTableUniqueDelegate

org.hibernate.dialect.unique.CreateTableUniqueDelegate

org.hibernate.dialect.unique.SkipNullableUniqueDelegate

All Implemented Interfaces:

UniqueDelegate

public class SkipNullableUniqueDelegate
extends CreateTableUniqueDelegate

A UniqueDelegate that only creates unique constraints on not-null columns, and ignores requests for uniqueness for nullable columns.

Needed because unique constraints on nullable columns in Sybase always consider null values to be non-unique. There is simply no way to create a unique constraint with the semantics we want on a nullable column in Sybase.

You might argue that this behavior is bad because if the programmer explicitly specifies an @UniqueKey, then we should damn well respect their wishes. But the simple answer is that the user should have also specified @Column(nullable=false) if that is what they wanted. A unique key on a nullable column just really doesn't make sense in Sybase, except, perhaps, in some incredibly corner cases.

Field Summary

Fields inherited from class org.hibernate.dialect.unique.AlterTableUniqueDelegate

dialect

Constructor Summary

Constructors

Constructor	Description
SkipNullableUniqueDelegate(Dialect dialect)

Method Summary

Modifier and Type	Method	Description
protected void	appendUniqueConstraint(StringBuilder fragment, UniqueKey uniqueKey)
String	getAlterTableToAddUniqueKeyCommand(UniqueKey uniqueKey, Metadata metadata, SqlStringGenerationContext context)	Get the alter table command used to create the given unique key constraint, or return the empty string if the constraint was already included in the create table statement by UniqueDelegate.getTableCreationUniqueConstraintsFragment(org.hibernate.mapping.Table, org.hibernate.boot.model.relational.SqlStringGenerationContext).
String	getAlterTableToDropUniqueKeyCommand(UniqueKey uniqueKey, Metadata metadata, SqlStringGenerationContext context)	Get the alter table command used to drop the given unique key which was previously created by UniqueDelegate.getAlterTableToAddUniqueKeyCommand(org.hibernate.mapping.UniqueKey, org.hibernate.boot.Metadata, org.hibernate.boot.model.relational.SqlStringGenerationContext).
String	getColumnDefinitionUniquenessFragment(Column column, SqlStringGenerationContext context)	Get the SQL fragment used to make the given column unique as part of its column definition, usually just " unique", or return an empty string if uniqueness does not belong in the column definition.

Methods inherited from class org.hibernate.dialect.unique.CreateTableUniqueDelegate

getTableCreationUniqueConstraintsFragment

Methods inherited from class org.hibernate.dialect.unique.AlterTableUniqueDelegate

uniqueConstraintSql

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SkipNullableUniqueDelegate

public SkipNullableUniqueDelegate(Dialect dialect)

Method Detail

getColumnDefinitionUniquenessFragment

public String getColumnDefinitionUniquenessFragment(Column column,
                                                    SqlStringGenerationContext context)

Description copied from interface: UniqueDelegate

Get the SQL fragment used to make the given column unique as part of its column definition, usually just " unique", or return an empty string if uniqueness does not belong in the column definition.

This is for handling single columns explicitly marked unique, not for dealing with unique keys.

Specified by:

getColumnDefinitionUniquenessFragment in interface UniqueDelegate

Overrides:

getColumnDefinitionUniquenessFragment in class CreateTableUniqueDelegate

Parameters:

column - The column to which to apply the unique

context - A context for SQL string generation

Returns:

The fragment (usually "unique"), empty string indicates the uniqueness will be indicated using a different approach

appendUniqueConstraint

protected void appendUniqueConstraint(StringBuilder fragment,
                                      UniqueKey uniqueKey)

Overrides:

appendUniqueConstraint in class CreateTableUniqueDelegate

getAlterTableToAddUniqueKeyCommand

public String getAlterTableToAddUniqueKeyCommand(UniqueKey uniqueKey,
                                                 Metadata metadata,
                                                 SqlStringGenerationContext context)

Description copied from interface: UniqueDelegate

Get the alter table command used to create the given unique key constraint, or return the empty string if the constraint was already included in the create table statement by UniqueDelegate.getTableCreationUniqueConstraintsFragment(org.hibernate.mapping.Table, org.hibernate.boot.model.relational.SqlStringGenerationContext).

Specified by:

getAlterTableToAddUniqueKeyCommand in interface UniqueDelegate

Overrides:

getAlterTableToAddUniqueKeyCommand in class CreateTableUniqueDelegate

Parameters:

uniqueKey - The UniqueKey instance. Contains all information about the columns

metadata - Access to the bootstrap mapping information

context - A context for SQL string generation

Returns:

The alter table command

getAlterTableToDropUniqueKeyCommand

public String getAlterTableToDropUniqueKeyCommand(UniqueKey uniqueKey,
                                                  Metadata metadata,
                                                  SqlStringGenerationContext context)

Description copied from interface: UniqueDelegate

Get the alter table command used to drop the given unique key which was previously created by UniqueDelegate.getAlterTableToAddUniqueKeyCommand(org.hibernate.mapping.UniqueKey, org.hibernate.boot.Metadata, org.hibernate.boot.model.relational.SqlStringGenerationContext).

Specified by:

getAlterTableToDropUniqueKeyCommand in interface UniqueDelegate

Overrides:

getAlterTableToDropUniqueKeyCommand in class CreateTableUniqueDelegate

Parameters:

uniqueKey - The UniqueKey instance. Contains all information about the columns

metadata - Access to the bootstrap mapping information

context - A context for SQL string generation

Returns:

The alter table command