CREATE VIEW employee_yos AS SELECT employee_id, first_name || ' ' || last_name full_name, FLOOR( months_between( CURRENT_DATE, hire_date )/ 12 ) yos FROM employees; Code language: SQL (Structured Query Language) (sql) In this example, we did not define the column names for the v...
CREATE VIEW emp_region_view AS SELECT (e.emp_name,e.emp_id,r.rname,r.objectid,r.region) FROM employees e,region r WHERE e.emp_id = r.emp_id; 授予视图权限 您可将视图权限授予特定用户,而无需授予这些用户对基表(employees 和 regions)的访问权限。在本例中,将两个视图的 sele...
若数据库版本小于 12.2.0.1 时,则示例数据位于 EXAMPLE 表空间。 12c 版本的 CDB 数据库不再包含示例数据库和示例表空间。 12.1.0.2 版本: 18c 的版本: 静默创建示例 PDB : dbca -silent -createpluggabledatabase -sourceDB cdb1212 -pdbName pdbsample -createAsClone True -createPDBFrom RMANBACKUP -pdbBa...
Use the SQL command DROP VIEW to drop a view. For example: DROP VIEW Accounts_staff;Modifying a Join View Oracle allows you, with some restrictions, to modify views that involve joins. Consider the following simple view: CREATE VIEW Emp_view AS SELECT Ename, Empno, deptno FROM Emp;...
create [or replace] view 视图名 [列别名1[,列别名2]...)] as <视图对应的子查询语句> [with check option] [constraint 约束名] [with read only] with check option:指定视图上定义的check约束 with read only:定义只读视图 若定义时不提供列别名则使用子查询的列名或列别名;若视图子查询包含函数或表达...
defines the thresholdofthe estimated leaf block count--to be smaller than the supplied fractionofthe current size.--vTargetUse:Supplied percentage utilisation.For example90%equates to thedefaultpctfree10--vHistRet:Defines the numberofrecords to keepintheINDEX_HISTtableforeach index entry--CREATEOR...
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where tablespace_name notin('SYSTEM','SYSAUX','UNDOTBS1','TEMP','EXAMPLE');select owner,tablespace_name,count(*)from dba_segments where tablespace_name notin('SYSTEM','SYSAUX','UNDOTBS1','TEMP','EXAMPLE')group by owner,tablespace_name order by tablespace_name; ...
create directory lob_dir AS '/tmp'; grant read on directory lob_dir to HR; 最后,使用编辑器创建 /tmp/example.txt 文件,其中包含您所选的任何虚拟文本。 为了深入了解用于 LOB 表的默认的表创建选项,试着用 DBMS_METADATA.GET_DDL 过程生成全部 DDL: ...
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