4、进行集合操作的查询,结尾处可以自行选择是否加ORDER BY关键字,进行自定义排序; 5、如果两个查询中都有NULL这个空值元素,两个查询在进行Union合并操作时,只会显示一个NULL元素行。虽然NULL<>NULL,但是Oracle在执行集合操作时,内部进行隐式函数处理:sys_op_map_nonnull(null) 函数解释官方扩展: In Oracle, NULL ...
select * from emp where sys_op_map_nonnull(comm) = sys_op_map_nonnull(null); create index emp_comm_i on emp(sys_op_map_nonnull(comm));
An alternative is to use the undocumentedSYS_OP_MAP_NONNULLfunction to allow null matches. SELECT id, 'col1=col2' FROM null_test_tab WHERE SYS_OP_MAP_NONNULL(col1) = SYS_OP_MAP_NONNULL(col2); ID 'COL1=COL --- --- 3 col1=col2 4 col1=col2 2 rows selected. SQL> Remember...
空值相等的函数 sys_op_map_nonnull(null) select * from emp where sys_op_map_nonnull(null)=sys_op_map_nonnull(null); 十二 事务 事务是指一组逻辑操作单元,使数据从一种状态变换到另一种状态,为确保数据库中数据的一致性,数据的操纵应当是离散的成组的逻辑单元,当全部完成时,数据的一致性可以保持,当这...
4 - access(SYS_OP_MAP_NONNULL("ORDER_ID")=SYS_OP_MAP_NONNULL("AV$0"."GB0")) 5 - filter("ORDER_SUMMARY_RTMV"."ORDER_ID"=1) 10 - filter((("MAS$"."OLD_NEW$$"='N' AND "MAS$"."SEQ$$"="MAS$"."MAXSEQ$$") OR
In Oracle Developer Studio, –M selects a linker map file. –B(static| dynamic) –Wl,–B(static| dynamic) GNU Linker supports this behavior, but gcc does not. Use –Wl to pass the option to GNU ld. In gcc, –B performs another function. –G –shared When producing a shared ...
Type of the transaction. Value is a bitmap (for example, 2 active transaction, 0X10 space transaction, 0X20 recursive transaction). 39 number UGA_Memory User Global Area session memory 100 number Wait_Time Elapsed time, in hundredths of seconds, for the wait event 21 number 1...
一、引入 1 /** 2 * Description:新建一个类作为map的key 3 */ 4 public class ...
在nacos 配置redisson nacos配置oracle数据库,从2.2.0版本开始,可通过SPI机制注入多数据源实现插件,并在引入对应数据源实现后,便可在Nacos启动时通过读取application.properties配置文件中spring.datasource.platform配置项选择加载对应多数据源插件.本文档详细介绍一个多
SYS_CONNECT_BY_PATH (hierarchical),SYS_CONTEXT (environment),SYS_DBURIGEN,SYS_EXTRACT_UTC,SYS_GUID (identifier),SYS_OP_DESCEND,SYS_OP_DISTINCT,SYS_OP_GUID,SYS_OP_LBID,SYS_OP_MAP_NONNULL,SYS_OP_RAWTONUM,SYS_OP_RPB,SYS_OP_TOSETID,SYS_TYPEID,SYS_XMLAGG,SYS_XMLGEN,SYSDATE,SYSTIMESTAMP,...