在数据库中,优化器之所以重要,是因为SQL是一种声明式的语言,只是告诉用户需要什么数据,但获取数据往往有多条路径,路径间代价差异可能会很大,优化器则是负责快速、高效的找出获取数据的最佳执行路径,是数据库的大脑,可谓得优化器者得数据库天下。 论文An Overview of Query Optimization in Relational Systems写于1998年...
/conectar.php");$query = $_REQUEST['query']; $sql = mysql_query ("SELECT* F 浏览2提问于2014-01-21得票数 0 1回答 MySQL InnoDB CASCADE? 、、、 我已经设置了一些带有外键的表,但它们的行为并不像预期的那样。下面是我的表CREATE语句: section_id INT NOT NULL AUTO_INCREMENT, FOREIGN KEY(se...
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The physical standby in Europe forwards the redo to the three logical standby databases in the Europe manufacturing plants providing local access to corporate data for end-user query and reports. Room for future growth is built in - additional standby databases can be deployed in Europe without an...
cmdidUpdateQuery cmdidVBEFirst cmdidVerifySQL cmdidVertSpaceConcatenate cmdidVertSpaceDecrease cmdidVertSpaceIncrease cmdidVertSpaceMakeEqual cmdidViewBarView1 cmdidViewBarView10 cmdidViewBarView11 cmdidViewBarView12 cmdidViewBarView13 cmdidViewBarView14 cmdidViewBarView15 cmdidViewBa...
BoundariesCreateCascadeDeleteJobQueryParamProperties BoundariesCreateOrUpdate BoundariesCreateOrUpdate200Response BoundariesCreateOrUpdate201Response BoundariesCreateOrUpdateBodyParam BoundariesCreateOrUpdateDefaultHeaders BoundariesCreateOrUpdateDefaultResponse BoundariesCreateOrUpdateMediaTyp...
BoundariesCreateCascadeDeleteJobQueryParamProperties BoundariesCreateOrUpdate BoundariesCreateOrUpdate200Response BoundariesCreateOrUpdate201Response BoundariesCreateOrUpdateBodyParam BoundariesCreateOrUpdateDefaultHeaders BoundariesCreateOrUpdateDefaultResponse BoundariesCreateOrUpdateMediaTypesParam BoundariesCreateOrUpdateParamet...
BoundariesCreateCascadeDeleteJobQueryParamProperties BoundariesCreateOrUpdate BoundariesCreateOrUpdate200Response BoundariesCreateOrUpdate201Response BoundariesCreateOrUpdateBodyParam BoundariesCreateOrUpdateDefaultHeaders BoundariesCreateOrUpdateDefaultResponse BoundariesCreateOrUpdateMediaTypesParam BoundariesCrea...
SQL> create user jeanron identified by jeanron; User created. SQL> drop user jeanron; User dropped. ###可以看到删除是不需要cascade选项的。如果想加cascade选项,会不会有问题呢。SQL> create user jeanron identified by jeanron; User created. SQL> drop user jeanron cascade; User dropped. ###...
You have a primary database in a city in the United States and you wish to deploy three complete replicas of this database to be used for end-user query and reporting in three different manufacturing plants in Europe. Your objective is to eliminate the need for users and applications at yo...