第四章：索引
1.creating function-based indexes
sql> create index summit.item_quantity on summit.item(quantity-quantity_shipped);2.create a b-tree index
sql> create [unique] index index_name on table_name(column,.. asc/desc) tablespace
sql> tablespace_name [pctfree integer] [initrans integer] [maxtrans integer]
sql> [logging | nologging] [nosort] storage(initial 200k next 200k pctincrease 0
sql> maxextents 50);
3.pctfree(index)=(maximum number of rows-initial number of rows)*100/maximum number of rows
4.creating reverse key indexes
sql> create unique index xay_id on xay(a) reverse pctfree 30 storage(initial 200k
sql> next 200k pctincrease 0 maxextents 50) tablespace indx;
5.create bitmap index
sql> create bitmap index xay_id on xay(a) pctfree 30 storage( initial 200k next 200k
sql> pctincrease 0 maxextents 50) tablespace indx;
6.change storage parameter of index
sql> alter index xay_id storage (next 400k maxextents 100);
7.allocating index space
sql> alter index xay_id allocate extent(size 200k datafile ''c:/oracle/index.dbf'');
8.alter index xay_id deallocate unused;
第五章：约束1.define constraints as immediate or deferred
sql> alter session set constraint[s] = immediate/deferred/default;
set constraint[s] constraint_name/all immediate/deferred;
2. sql> drop table table_name cascade constraints
sql> drop tablespace tablespace_name including contents cascade constraints
3. define constraints while create a table
sql> create table xay(id number(7) constraint xay_id primary key deferrable
sql> using index storage(initial 100k next 100k) tablespace indx);
primary key/unique/references table(column)/check
4.enable constraints
sql> alter table xay enable novalidate constraint xay_id;
5.enable constraints
sql> alter table xay enable validate constraint xay_id;
