一些常用的sql语句

添加一列
alter table 表名 add 列名 类型;
添加一行
insert into 表名 values ('','','');


删除一行
delete from 表名 where 条件;
删除一列
ALTER TABLE 表名 DROP COLUMN 列名;


alter table student
drop constraint pk_student 
--去掉这个表的主键

alter table student
add constraint pk_student primary key clustered (studentid, seq)
--重新设置表的主键


修改字段的值
update 表名 set 字段='xxxx' where 字段='yyy'

根据一张表创建另一张表（也可以在原表上加一定的条件）
select * into a_s_unit from  s_unit weher id in(1,2,3,4) ;

oracle:

create table  a_s_unit as select * from s_unit weher id in(1,2,3,4) ;



使用rename关键字来实现字段名的修改:alter table 表名 rename column旧的字段名 to 新的字段名名;
使用modify关键字来实现对数据类型的修改:alter table 表名 modify 字段名 数据类型;


oralce 修改有数据的列的类型

1，建立临时列
alter table S_UNIT_INCOME add income_fee_bak decimal(18,6);

2.把修改的列的数据导入到临时列
update s_unit_income set income_fee_bak=income_fee;

3.把列的数据全部修改为空
update s_unit_income set income_fee='';

4.修改列的类型
alter table S_UNIT_INCOME modify income_fee decimal(18,6);

5.把临时列的数据导入到修改的列
update s_unit_income set income_fee=income_fee_bak;

6.删除临时列
alter table S_UNIT_INCOME drop column income_fee_bak;


大字段修改

1，建立临时列
alter table s_project add iintro_bak varchar(4000);

2.把修改的列的数据导入到临时列
update s_project set iintro_bak=intro;

3.删除列
ALTER TABLE s_project DROP COLUMN intro;

4.把临时列命名为删除的列
ALTER TABLE s_project RENAME COLUMN iintro_bak TO intro;









增加主键约束
alter table S_PROJECT add constraint PK__S_PROJECT primary key(ID);

oracle修改数据库密码
alter user 数据库名 identified by 密码;



获取当前时间
cast((Datename(year,GetDate())+'-'+Datename(month,GetDate())+'-'+Datename(day,GetDate())) as datetime)



查表
select * from INFORMATION_SCHEMA.TABLES where TABLE_TYPE='base table'



存储过程

---------------------------------------------------
declare @unitId varchar(32),@honorId varchar(32)
declare project_cursor CURSOR FOR SELECT ID FROM s_honor where unit_id is null  and id in(select honor_id from s_honor_author where author_type='1')
OPEN project_cursor
FETCH NEXT FROM project_cursor INTO @honorId
WHILE @@FETCH_STATUS=0
BEGIN
declare member_cursor CURSOR for select author_unit_id from s_honor_author where honor_id = @honorId and author_type='1' order by order_id
OPEN member_cursor
FETCH NEXT FROM member_cursor INTO @unitId
update s_honor set unit_id=@unitId where id=@honorId
CLOSE member_cursor
DEALLOCATE member_cursor
print ' honorId :'+@honorId +' unitId:'+@unitId
FETCH NEXT FROM project_cursor
INTO @honorId
END
CLOSE project_cursor
DEALLOCATE project_cursor


select ','+name from s_perosn for xml path('')，