Oracle中使用View能缩短查询的时间么

Posted 2023-03-22

我有一个View是多个表级联的数据，请问直接查询View能否缩短查询级联数据的时间？

普通的View不可以。因为普通的View就是相当于一个映射。实际执行时，还是从各个实体表中取数据。
不过可以试试物化View，在物化View下，各个实体表取得的数据已经作成了一个物化表，从物化View中取得数据相当于从一个实体表中取得数据。这样速度会快一些。 参考技术A 不能 参考技术B 好像可以吧。

缩短并优化多个表的查询

我在Java中使用PreparedStatement。我有来自多个表的SQL查询。如果可能的话，我怎样才能使这个查询更短更优化？ DB是“Oracle 12c数据库”。另外我的任务是使查询sql-injection安全并防止注入。

preparedStatement = connection.prepareStatement("delete from " +
            "TBL_ORG_DATA, " +
            "TBL_ORG_CONTACTS, " +
            "TBL_HEALTH_SERVICE, " +
            "TBL_EDUCATION, " +
            "TBL_LENGTH_WORK, " +
            "TBL_CONTRACTS, " +
            "TBL_EVENTS, " +
            "TBL_TRADE_UNIONS, " +
            "TBL_COMMITTEES, " +
            "TBL_HEALTH_CHECK, " +
            "TBL_ACCIDENTS, " +
            "TBL_VICTIMS, " +
            "TBL_ACCIDENTS_DAMAGE, " +
            "TBL_ATTESTATION, " +
            "TBL_ATTESTATION_FIVE_YEAR, " +
            "TBL_TRANING, " +
            "TBL_TRAINING_MANAGER, " +
            "TBL_TRANING_THREE_YEAR, " +
            "TBL_MANAGEMENT " +
            "where TBL_ORG_DATA.ORG_ID = ? AND\n" +
            "TBL_ORG_CONTACTS.ORG_ID = ? AND\n" +
            "TBL_HEALTH_SERVICE.ORG_ID = ? AND\n" +
            "TBL_EDUCATION.ORG_ID = ? AND\n" +
            "TBL_LENGTH_WORK.ORG_ID = ? AND\n" +
            "TBL_CONTRACTS.ORG_ID = ? AND\n" +
            "TBL_EVENTS.ORG_ID = ? AND\n" +
            "TBL_TRADE_UNIONS.ORG_ID = ? AND\n" +
            "TBL_COMMITTEES.ORG_ID = ? AND\n" +
            "TBL_HEALTH_CHECK.ORG_ID = ? AND\n" +
            "TBL_ACCIDENTS.ORG_ID = ? AND\n" +
            "TBL_VICTIMS.ORG_ID = ? AND\n" +
            "TBL_ACCIDENTS_DAMAGE.ORG_ID = ? AND\n" +
            "TBL_ATTESTATION.ORG_ID = ? AND\n" +
            "TBL_ATTESTATION_FIVE_YEAR.ORG_ID = ? AND\n" +
            "TBL_TRANING.ORG_ID = ? AND\n" +
            "TBL_TRAINING_MANAGER.ORG_ID = ? AND\n" +
            "TBL_TRANING_THREE_YEAR.ORG_ID = ? AND\n" +
            "TBL_MANAGEMENT.ORG_ID = ? AND\n" +                
            "TBL_ORG_DATA.DATE_PERIOD = ? AND\n" +
            "TBL_ORG_CONTACTS.DATE_PERIOD = ? AND\n" +
            "TBL_HEALTH_SERVICE.DATE_PERIOD= ? AND\n" +
            "TBL_EDUCATION.DATE_PERIOD= ? AND\n" +
            "TBL_LENGTH_WORK.DATE_PERIOD = ? AND\n" +
            "TBL_CONTRACTS.DATE_PERIOD = ? AND\n" +
            "TBL_EVENTS.DATE_PERIOD = ? AND\n" +
            "TBL_TRADE_UNIONS.DATE_PERIOD = ? AND\n" +
            "TBL_COMMITTEES.DATE_PERIOD = ? AND\n" +
            "TBL_HEALTH_CHECK.DATE_PERIOD = ? AND\n" +
            "TBL_ACCIDENTS.DATE_PERIOD = ? AND\n" +
            "TBL_VICTIMS.DATE_PERIOD = ? AND\n" +
            "TBL_ACCIDENTS_DAMAGE.DATE_PERIOD = ? AND\n" +
            "TBL_ATTESTATION.DATE_PERIOD = ? AND\n" +
            "TBL_ATTESTATION_FIVE_YEAR.DATE_PERIOD = ? AND\n" +
            "TBL_TRANING.DATE_PERIOD = ? AND\n" +
            "TBL_TRAINING_MANAGER.DATE_PERIOD = ? AND\n" +
            "TBL_TRANING_THREE_YEAR.DATE_PERIOD = ? AND\n" +
            "TBL_MANAGEMENT.DATE_PERIOD = ?");

答案

据我所知在Oracle中你必须为每个表创建单独的delete命令。

delete from a where org_id = 101 and date_period = date '2018-05-25';
delete from b where org_id = 101 and date_period = date '2018-05-25';

如果你可以修改表格，那么你可以使用约束on delete cascade。我不知道你的表是如何组织的，但是如果在其中一个表中你可以定义唯一约束，那么rest可能依赖于它，就像这里：

create table a (
    id number primary key, org_id number, date_period date, cola varchar2(5),
    constraint uq_org_id_period unique (org_id, date_period) );
insert into a values (1, 101, date '2018-05-25', 'DEL');
insert into a values (2, 101, date '2018-05-26', 'PQR');
insert into a values (3, 102, date '2018-06-17', 'CBA');

create table b (
    id number primary key, org_id number, date_period date, colb varchar2(5),
    constraint fk_org_id_period 
        foreign key (org_id, date_period) 
        references a(org_id, date_period) on delete cascade);
insert into b values (1, 101, date '2018-05-26', 'AAXXX');
insert into b values (2, 102, date '2018-06-17', 'PCCQR');
insert into b values (3, 101, date '2018-05-25', 'DEL1');
insert into b values (4, 101, date '2018-05-25', 'DEL2');
insert into b values (5, 102, date '2018-06-17', 'XYZYX');

现在，如果您运行：

delete from a where (org_id, date_period) in ((101, date '2018-05-25'));

不仅会删除表a中的第1行，还会删除b中的第3行和第4行。您也可以使用触发器，但约束更合适。