Oracle数据库命令速查手册-表

1.create a table 
sql> create table table_name (column datatype,column datatype]....) 
sql> tablespace tablespace_name [pctfree integer] [pctused integer] 
sql> [initrans integer] [maxtrans integer]sql> storage(initial 200k next 200k pctincrease 0 maxextents 50) 
sql> [logging|nologging] [cache|nocache] 
2.copy an existing table 
sql> create table table_name [logging|nologging] as subquery 
3.create temporary table 
sql> create global temporary table xay_temp as select * from xay; 
on commit preserve rows/on commit delete rows 
4.pctfree = (average row size - initial row size) *100 /average row size 
pctused = 100-pctfree- (average row size*100/available data space) 
5.change storage and block utilization parameter 
sql> alter table table_name pctfree=30 pctused=50 storage(next 500k minextents 2 maxextents 100);
6.manually allocating extents 
sql> alter table table_name allocate extent(size 500k datafile 'c:/oracle/data.dbf');
7.move tablespace 
sql> alter table employee move tablespace users; 
8.deallocate of unused space 
sql> alter table table_name deallocate unused [keep integer] 
9.truncate a table 
sql> truncate table table_name; 
10.drop a table 
sql> drop table table_name [cascade constraints]; 
11.drop a column 
sql> alter table table_name drop column comments cascade constraints checkpoint 1000; 
alter table table_name drop columns continue; 
12.mark a column as unused 
sql> alter table table_name set unused column comments cascade constraints; 
alter table table_name drop unused columns checkpoint 1000; 
alter table orders drop columns continue checkpoint 1000 
data_dictionary : dba_unused_col_tabs