这可能是由小往大 (ascending) 或是由大往小 (descending)。在这种情况下,我们就可以运用 ORDER BY 这个指令来达到我们的目的。 ORDER BY 的语法如下: SELECT "栏位名" FROM "表格名" [WHERE "条件"] ORDER BY "栏位名" [ASC, DESC] [] 代表 WHERE 子句不是一定需要的。不过,如果 WHERE 子句存在的...
|* 2 | INDEX RANGE SCAN | IND_DEPT2 | 4 | | 1 (0)| 00:00:01 | ---Index Range Scans 如果语句中符合该条件进行范围扫,后面有排序的,将会进行索引范围降序扫描。 INDEX RANGE SCAN DESCENDING例子: 03:04:16 SQL> select * from scott.dept2 where DEPTNO>1 order by 1 desc; Execution Plan...
NULLS FIRST | NULLS LAST Specify whether returned rows containing nulls should appear first or last in the ordering sequence. NULLS LAST is the default for ascending order, and NULLS FIRST is the default for descending order....
ORDER BY field1 [ASC | DESC], field2 [ASC | DESC], ... For example, the following query sorts the results of the `employees` table by the `last_name` field in ascending order and the`first_name` field in descending order: SELECT. FROM employees. ORDER BY last_name ASC, first_nam...
SQL> desc t_order Name Null? Type --- --- --- ID NUMBER CDATE DATE 1. 2. 3. 4. 5. 如果不带order by,查询返回的结果集顺序就是如下, P.S. 关于数据检索顺序的问题,可以参考《Oracle数据顺序问题》。 SQL> select * from t_order; ID CDATE --- --- 1 2021-01-04...
(0)| 00:00:01 | 9 |00:00:00.01 | 5 | | 3 | TABLE ACCESS BY INDEX ROWID| T_O | 1 | 100K| 3 (0)| 00:00:01 | 9 |00:00:00.01 | 5 | | 4 | INDEX FULL SCAN DESCENDING| IDX_TO_01 | 1 | 9 | 2 (0)| 00:00:01 | 9 |00:00:00.01 | 3 | ---...
对于升序索引(Ascending Indexes),数据库按升序排列的顺序存储数据。索引默认按照升序存储列值。默认情况下,字符数据按每个字节中包含的二进制值排序,数值数据按从小到大排序,日期数据从早到晚排序。 降序索引(Descending Indexes)将存储在一个特定的列或多列中的数据按降序排序。创建降序索引时使用DESC关键字,如下所示...
Indexes, by default, are stored in ascending order. Usually, this scan is used when ordering data in a descending order to return the most recent data first, or when seeking a value less than a specified value. 可以使用索引范围扫描来避免排序 SQL> alter system flush buffer_cache; 系统已...
If your query contains "order by descending", the descending index can avoid a sort operation. The simplest case is where you're searching a range of values, sorting these descending and another column.For example, finding the orders for customer_ids in a given range. Return these ids in ...
Cause: A column was specified in a condition or ORDER BY which is not part of the CTXCAT index. Action: DRG-10846 order by columns must be all ascending or all descending Cause: An ORDER BY clause was specified which has some columns ascending and some descending. This is not currently...