zoukankan      html  css  js  c++  java
  • SAVEPOINT

    from:
    http://www.postgresql.org/docs/8.4/interactive/sql-savepoint.html

    SAVEPOINT
    Name
    SAVEPOINT -- define a new savepoint within the current transaction
    Synopsis

    SAVEPOINT savepoint_name

    Description

    SAVEPOINT establishes a new savepoint within the current transaction.

    A savepoint is a special mark inside a transaction that allows all commands that are executed after it was established to be rolled back, restoring the transaction state to what it was at the time of the savepoint.
    Parameters

    savepoint_name

        The name to give to the new savepoint.

    Notes

    Use ROLLBACK TO SAVEPOINT to rollback to a savepoint. Use RELEASE SAVEPOINT to destroy a savepoint, keeping the effects of commands executed after it was established.

    Savepoints can only be established when inside a transaction block. There can be multiple savepoints defined within a transaction.
    Examples

    To establish a savepoint and later undo the effects of all commands executed after it was established:

    BEGIN;
        INSERT INTO table1 VALUES (1);
        SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (2);
        ROLLBACK TO SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (3);
    COMMIT;

    The above transaction will insert the values 1 and 3, but not 2.

    To establish and later destroy a savepoint:

    BEGIN;
        INSERT INTO table1 VALUES (3);
        SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (4);
        RELEASE SAVEPOINT my_savepoint;
    COMMIT;

    The above transaction will insert both 3 and 4.
    Compatibility

    SQL requires a savepoint to be destroyed automatically when another savepoint with the same name is established. In PostgreSQL, the old savepoint is kept, though only the more recent one will be used when rolling back or releasing. (Releasing the newer savepoint will cause the older one to again become accessible to ROLLBACK TO SAVEPOINT and RELEASE SAVEPOINT.) Otherwise, SAVEPOINT is fully SQL conforming.
    See Also
    BEGIN, COMMIT, RELEASE SAVEPOINT, ROLLBACK, ROLLBACK TO SAVEPOINT
    Prev    Home    Next
    ROLLBACK TO SAVEPOINT    Up    SELECT
    User Comments

    No comments could be found for this page.

    New comments cannot be added to old documentation versions.

  • 相关阅读:
    IOS 面试题(不断更新...)
    IOS 数字日期转化为字符串
    C#汉字生成简拼
    ObjectiveC 深浅拷贝
    数组遍历方法forEach 和 map 的区别
    COJ1174(Shining Gems)
    POJ1062(昂贵的聘礼)
    HDOJ1879(继续畅通工程)
    最短路径经典题集(转载)
    HDOJ1863(畅通工程)
  • 原文地址:https://www.cnblogs.com/luoyaoquan/p/2140592.html
Copyright © 2011-2022 走看看