advanced oracle sql tuning

Oracel provides three types of collection operations: Each is and (UNION), intersection (INTERSECT), poor (minus)Union: Merges the results of multiple operations into a single query result, returning the union of query results and proactively removing the repeated portions.UNION all: Merges the results of multiple operations into a single query result, but retains repeated content.INTERSECT: Returns the same part of multiple operation results.Minus: Returns the difference set of two query result

to this problem error. In addition, two new XML functions are added to the mysql5.1 version, which can also be used to make an error. Mysql> SELECT * FROM article WHERE id = 1 and extractvalue (1, concat (0x5c, (select pass from admin limit 1)); Error 1105 (HY000): XPATH syntax error: ' \admin888 ' mysql> select * FROM article WHERE id = 1 and 1= (Updatexml (1,Concat (0x5e24, (select pass from admin limit 1), 0x5e24), 1); Error 1105 (HY000): XPATH syntax ERROR: ' ^ $admin 888^$ ' In other datab

In this Document Goal Solution 1. Master List showing sample code for APIs in Product Data Hub 2. FAQs A. Need API to load Item Catalog Category people, associating ICC with Templates Match Rules, was there an API for th is purpose? References Applies To:Oracle Product hub-version 12.0.4

Tags: http original How many star technology share from company demand advancedLuffy: "Transfer the original CSDN blog to the blog park!" ”Some time ago, the task that I was responsible for was involved in the business requirement of organization relationship, and I used Oracle recursive query. Here's a quick example. At work, we often encounter a relationship with a certain level of organization. For example, how many cities are saved, and there are

HAVING clause5. Sub-query in the FROM sectionThe FROM clause is used to specify the table to queryIf you want to continue the query in the results of a subquery, the subquery appears in the FROM clause, which is also called an inline view or an anonymous view.The handle query is treated as a view, but the view has no name and is valid only in the current SQL statement6. Sub-query in the Select sectionThe handle query is placed in the SELECT clause se

there's another way to do it: and MySQL's access to the primary key in the opposite way, MySQL is inserted by the table after the allocation of the growth of the value, and Oracle is obtained from the growth of the value of the insert record operation, before the execution of insert SQL must specify a primary key value to the record to insert so to be in the " Before "The time to get the self

perform large data processing in a single pass. The framework is designed to: a MapReduce cluster can be extended to thousands of nodes in a fault-tolerant manner. However, the MapReduce programming model has its own limitations. Its single input, two-stage data flows in strict, and the level is too low. For example, you would have to write custom code even for the most common operations. As a result, many programmers feel that the MapReduce framework is uncomfortable to use, preferring to use

stored procedures and custom functions, try not to use view, stored procedures cache execution plan, better performance, less limit On the split view, do not use aggregate functions, especially the aggregation function also contains the distinct In the view, if the WHERE clause can be added to the view, do not add to the view (because the call view will return all rows and then filter, Performance Killer, if you have added order by ...) SummaryIn this paper, the three types of view

13.1 Using Table AliasesIn addition to the column names and calculated fields, the aliases allow SQL to indicate aliases. There are two main reasons for this:(1) Shorten SQL statements(2) Allows the same table to be used more than once in a single SELECT statement.SELECT cust_name,cust_contactFROM Customers AS C,Orders AS O,OrderItems AS OIWHERE C.cust_id = O.cust_id AND OI.order_num = O.order_num A

that does not read data or execute plans, however, Oracle has provided a large number of built-in SQL optimization tools since 10 Gb. For example: ADDM, SQL Access Advisor, SQL Tuning Advisor, Automatic SQL