程序包 org.hibernate.dialect.unique

接口 UniqueDelegate

所有已知实现类:

DB2UniqueDelegate, DefaultUniqueDelegate, InformixUniqueDelegate, MySQLUniqueDelegate

public interface UniqueDelegate

Dialect-level delegate in charge of applying "uniqueness" to a column. Uniqueness can be defined in 1 of 3 ways:

1. Add a unique constraint via separate alter table statements. See getAlterTableToAddUniqueKeyCommand(org.hibernate.mapping.UniqueKey, org.hibernate.boot.Metadata). Also, see getAlterTableToDropUniqueKeyCommand(org.hibernate.mapping.UniqueKey, org.hibernate.boot.Metadata)
2. Add a unique constraint via dialect-specific syntax in table create statement. See getTableCreationUniqueConstraintsFragment(org.hibernate.mapping.Table)
3. Add "unique" syntax to the column itself. See getColumnDefinitionUniquenessFragment(org.hibernate.mapping.Column)

#1 & #2 are preferred, if possible; #3 should be solely a fall-back. See HHH-7797.

作者:

Brett Meyer

方法概要

修饰符和类型	方法	说明
String	getAlterTableToAddUniqueKeyCommand(UniqueKey uniqueKey, Metadata metadata)	Get the SQL ALTER TABLE command to be used to create the given UniqueKey.
String	getAlterTableToDropUniqueKeyCommand(UniqueKey uniqueKey, Metadata metadata)	Get the SQL ALTER TABLE command to be used to drop the given UniqueKey.
String	getColumnDefinitionUniquenessFragment(Column column)	Get the fragment that can be used to make a column unique as part of its column definition.
String	getTableCreationUniqueConstraintsFragment(Table table)	Get the fragment that can be used to apply unique constraints as part of table creation.

方法详细资料

getColumnDefinitionUniquenessFragment

String getColumnDefinitionUniquenessFragment(Column column)

Get the fragment that can be used to make a column unique as part of its column definition.

This is intended for dialects which do not support unique constraints

参数:

column - The column to which to apply the unique

返回:

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

getTableCreationUniqueConstraintsFragment

String getTableCreationUniqueConstraintsFragment(Table table)

Get the fragment that can be used to apply unique constraints as part of table creation. The implementation should iterate over the UniqueKey instances for the given table (see Table.getUniqueKeyIterator() and generate the whole fragment for all unique keys

Intended for Dialects which support unique constraint definitions, but just not in separate ALTER statements.

参数:

table - The table for which to generate the unique constraints fragment

返回:

The fragment, typically in the form ", unique(col1, col2), unique( col20)". NOTE: The leading comma is important!

getAlterTableToAddUniqueKeyCommand

String getAlterTableToAddUniqueKeyCommand(UniqueKey uniqueKey,
                                          Metadata metadata)

Get the SQL ALTER TABLE command to be used to create the given UniqueKey.

参数:

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

metadata - Access to the bootstrap mapping information

返回:

The ALTER TABLE command

getAlterTableToDropUniqueKeyCommand

String getAlterTableToDropUniqueKeyCommand(UniqueKey uniqueKey,
                                           Metadata metadata)

Get the SQL ALTER TABLE command to be used to drop the given UniqueKey.

参数:

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

metadata - Access to the bootstrap mapping information

返回:

The ALTER TABLE command