STATEMENT | | 14M| 331M| 5935 (68)| 00:01:12 | | 1 | TEMP TABLE TRANSFORMATION | | | | | | | 2 | LOAD AS SELECT | SYS_TEMP_0FD9D679D_210BBB7 | | | | | | 3 | HASH GROUP BY | | 4823K| 50M| 2659 (8)| 00:00:32 | | 4 | TABLE ACCESS FULL | T_0424_1 |...
从执行计划看,虽然有用with as组织,Oracle优化器CBO还是将子查询展开了,作为一系列的join操作。由此:在单次使用with as的情况下,临时表预执行动作是不会进行的。 下面语句,我们同样抽取a,主查询中两次使用a查询结果。 SQL> explain plan for with a as (select emp.empno, emp.ename, dept.loc, emp.job fr...
11 - access("ID"<100) 注意观察上面的SQL语句,t1,t2表都被访问了2次,而且t1表2次访问都是同一条SQL语句(子查询),t2表也被访问了2次,但是2次的SQL结构基本一样,所以这里可以用with as优化该SQL WITH b AS (SELECT * FROM t1 WHERE id<100), a as (select * from t2 where id<100) SELECT a....
| 0 | SELECT STATEMENT | | 905 | 121K| 62428 (2)| 00:12:30 | | | | 1 | TEMP TABLE TRANSFORMATION | | | | | | | | | 2 | LOAD AS SELECT | DW_BO_ORDER | | | | | | | | 3 | PARTITION RANGE ALL | | 114K| 3228K| 9127 (2)| 00:01:50 | 1 | 5 | |* 4 |...
This SQL tutorial explains how to use the SQL CREATE TABLE AS statement with syntax and examples. You can also use the SQL CREATE TABLE AS statement to create a table from an existing table by copying the existing table's columns.
--select * from table(dbms_xplan.display(table_name=>'PLAN_TABLE',statement_id=>null,format=>'ALL')); 4、优化前耗时 15行耗时64秒 全部1000多条查完需要11分钟 5、奇怪的现象 结果集t查询出来速度是不慢的,数据量2000多条,但是跟fsl_trunkshipment_detail做关联查询的时候查询100条需要63秒,查询出...
decode(r4.paymentno,0,1,r4.paymentno)asPAYMENT_NO, p.productcodeasPOLICY_HOLDER_PRO, 1asPOLICY_HOLDER_NUM, 1asEFFECTIVE_INSURED_NUM, p.renewalpolicynoasFORMER_POLICY_NO, pro6.specialremarkasSPECIALRE_MARK, nullasREGULAR_CLEARING_MARK, ...
Basic Methods of Using the UPDATE Statement in MySQL The UPDATE Statement in SQL can be used in many ways to modify the existing record effectively. It can be used to update single or multiple columns, as well as with subqueries and JOINS. Method 1: Updating a Single Record in MySQL The...
我们都知道当我们使用PreparedStatement去写sql语句时,程序会对该条sql首先进行预编译,然后会将传入的字符串参数以字符串的形式去处理,即会在参数的两边自动加上单引号(’param’),而Statement则是直接简单粗暴地通过人工的字符串拼接的方式去写sql,那这样就很容易被sql注入。
The SQL JOIN statement is used to combine rows from two or more tables based on a related column between them. In this tutorial, you will learn about the SQL JOIN statement with the help of examples.