主键、外键、索引、重建索引

1.如何通过sql语句获取一个表的主键字段和自增字段

-- drop table #temp

create table #temp(table_name varchar(100),field_name varchar(50),sign varchar(10),keys int)

insert into #temp

SELECT

-- 表名=case when a.colorder=1 then d.name else '' end,

表名=d.name,

字段名=a.name,

标识=case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end,

主键=case when exists(SELECT 1 FROM sysobjects where xtype='PK' and name in (

SELECT name FROM sysindexes WHERE indid in(

SELECT indid FROM sysindexkeys WHERE id = a.id AND colid=a.colid

))) then 1 else 0 end

FROM syscolumns a

inner join sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'

order by a.id,a.colorder
select * from #temp

select table_name,sum(keys)

from #temp

group by table_name

having sum(keys)=0

select * from #temp

where table_name in(

select table_name from #temp

group by table_name

having sum(keys)=0)

2.主鍵與外鍵的關係

select b.name constname,c.name ForeignTable,d.name ForeignCol,

e.name refTable,f.name refCol

from sysforeignkeys a

inner join sysobjects b on a.constid=b.id

inner join sysobjects c on a.fkeyid=c.id

inner join syscolumns d on a.fkeyid=d.id and a.fkey=d.colid

inner join sysobjects e on a.rkeyid=e.id

inner join syscolumns f on a.rkeyid=f.id and a.rkey=f.colid

3.主鍵與外外鍵

CONSTRAINT [PK_dinner_request] PRIMARY KEY CLUSTERED

( [in_id]) ON [PRIMARY] ,

CONSTRAINT [FK_Dinner_request_Ticket_no] FOREIGN KEY

(

[ticket_no]

) REFERENCES [bread_ticket] ( [ticket_no])

4.把一列改成主鍵列

alter table bread_ticket add constraint PK_bread_ticket_Ticket_no primary key (ticket_no)

5.把兩列改成組合主鍵

alter table bank add constraint PK_bank primary key (bank_type,bank_id)

6.新加唯一鍵

alter table person add constraint UK_person UNIQUE (identity_no)

alter table tbArea add constraint UK_tbArea UNIQUE (remark)

7.增加外鍵

alter table dinner_request add constraint FK_dinner_request_Ticket_no foreign key (ticket_no) references bread_ticket (ticket_no)

8.刪除主鍵

Alter table tabPiecePrice drop constrain PK_ tabPiecePrice

9.修改某一列加默認值

ALTER TABLE [dbo].[tabOA_Person] ADD

CONSTRAINT [DF_tabOA_Person_new_affiche] DEFAULT (',') FOR [new_affiche]

10.通過建立索引來提高查詢速度

create index idx_person on person(person_name)

11.重建索引

DBCC INDEXDEFRAG (DB_MRP,PERSON,idx_person)

注:

参数1为数据库名

参数2为表名

参数3为要重建的原索引名

oracle 建表时加check约束或unique约束

1.加check约束或unique约束

create table temp(

gender varchar2(10) constraint ck_agents_gender check((gender='m')or(gender='f')),

cellphone nvarchar2(20) constraint uu_agents_cellphone unique);

2.加日期默认值

alter table tablename add col date1 default sysdate

alter table tablename modify col date1 default sysdate