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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package javax.jdo.annotations;
    18
    19  import java.lang.annotation.ElementType;
    20  import java.lang.annotation.Retention;
    21  import java.lang.annotation.RetentionPolicy;
    22  import java.lang.annotation.Target;
    23
    24  /**
    25   * Annotation for a database unique constraint. Used for database schema
    26   * generation to create unique constraints. Also used to reorder database
    27   * operations when flushing changes to avoid unique constraint violations.
    28   * Corresponds to the xml element "unique".
    29   *
    30   * @version 2.1
    31   * @since 2.1
    32   */
    33  @Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD})
    34  @Retention(RetentionPolicy.RUNTIME)
    35  public @interface Unique
    36  {
    37      /** Name of the unique constraint.
    38       * @return the name of the unique constraint
    39       */
    40      String name() default "";
    41
    42      /** Table for the unique constraint. This is needed iff annotating a type
    43       * where this unique constraint is not for the primary table for
    44       * the persistent class or interface.
    45       * @return the table on which the unique constraint is defined
    46       */
    47      String table() default "";
    48
    49      /** Whether this unique constraint is deferred until commit.
    50       * @return whether this unique constraint is deferred until commit
    51       */
    52      String deferred() default "";
    53
    54      /** Member (field and property) names that compose this unique constraint.
    55       * @return member names that compose this unique constraint
    56       */
    57      String[] members() default {};
    58
    59      /** Columns that compose this unique constraint.
    60       * @return columns that compose this unique constraint
    61       */
    62      Column[] columns() default {};
    63  }