1.JPA常見註解 2.JPA註解：表註釋

@org.hibernate.annotations.Table(appliesTo = "TableName",comment="表註釋")

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 
 */
package org.hibernate.annotations;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
importstatic java.lang.annotation.ElementType.TYPE;
importstatic java.lang.annotation.RetentionPolicy.RUNTIME;
/**
 * Complementary information to a table either primary or secondary.
 *
 * @author Emmanuel Bernard
 
 */
@Target({TYPE})
@Retention(RUNTIME)
public@interfaceTable{
/**
	 * name of the targeted table.
	 */
String appliesTo();
/**
	 * Indexes.
	 */
Index[] indexes()default{};
/**
	 * define a table comment.
	 */
String comment()default"";
/**
	 * Defines the Foreign Key name of a secondary table pointing back to the primary table.
 
	 */
ForeignKey foreignKey()default@ForeignKey( name="");
/**
	 * If set to JOIN, the default, Hibernate will use an inner join to retrieve a
	 * secondary table defined by a class or its superclasses and an outer join for a
	 * secondary table defined by a subclass.
	 * If set to select then Hibernate will use a
	 * sequential select for a secondary table defined on a subclass, which will be issued only if a row
	 * turns out to represent an instance of the subclass. Inner joins will still be used to retrieve a
	 * secondary defined by the class and its superclasses.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
FetchMode fetch()defaultFetchMode.JOIN;
/**
	 * If true, Hibernate will not try to insert or update the properties defined by this join.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
boolean inverse()defaultfalse;
/**
	 * If enabled, Hibernate will insert a row only if the properties defined by this join are non-null
	 * and will always use an outer join to retrieve the properties.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
boolean optional()defaulttrue;
/**
	 * Defines a custom SQL insert statement.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
SQLInsert sqlInsert()default@SQLInsert(sql="");
/**
	 * Defines a custom SQL update statement.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
SQLUpdate sqlUpdate()default@SQLUpdate(sql="");
/**
	 * Defines a custom SQL delete statement.
	 *
	 * <b>Only applies to secondary tables</b>
	 */
SQLDelete sqlDelete()default@SQLDelete(sql="");
}

3.JPA註解：欄位註釋

@Column(name="columnComment",columnDefinition="varchar(200) COMMENT '欄位註釋'")  

/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.  The Eclipse Public License is available
 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
 */
package javax.persistence;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
importstatic java.lang.annotation.ElementType.FIELD;
importstatic java.lang.annotation.ElementType.METHOD;
importstatic java.lang.annotation.RetentionPolicy.RUNTIME;
/**
 * Is used to specify the mapped column for a persistent property or field.
 * If no <code>Column</code> annotation is specified, the default values apply.
 *
 * <blockquote><pre>
 *    Example 1:
 *
 *    &#064;Column(name="DESC", nullable=false, length=512)
 *    public String getDescription() { return description; }
 *
 *    Example 2:
 *
 *    &#064;Column(name="DESC",
 *            columnDefinition="CLOB NOT NULL",
 *            table="EMP_DETAIL")
 *    &#064;Lob
 *    public String getDescription() { return description; }
 *
 *    Example 3:
 *
 *    &#064;Column(name="ORDER_COST", updatable=false, precision=12, scale=2)
 *    public BigDecimal getCost() { return cost; }
 *
 * </pre></blockquote>
 *
 *
 * @since Java Persistence 1.0
 */
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public@interfaceColumn{
/**
     * (Optional) The name of the column. Defaults to
     * the property or field name.
     */
String name()default"";
/**
     * (Optional) Whether the column is a unique key.  This is a
     * shortcut for the <code>UniqueConstraint</code> annotation at the table
     * level and is useful for when the unique key constraint
     * corresponds to only a single column. This constraint applies