SQLServer

Posted 2020-11-28 周公

create table person_base_info
(id int,
username varchar,
phone int
);

create table person_address
(
person_id int,
address_type varchar,
address_name varchar
);

alter table person_address alter column address_type varchar(12);
alter table person_address alter column address_name varchar(12);

alter table person_address add id int;

insert into person_base_info(id,username,phone) values(1,\'j\',135922);
insert into person_base_info values(2,\'k\',28);
insert into person_base_info values(3,\'j\',25);

insert into person_base_info values(4,\'l\',25);

select * from person_base_info

insert into person_address(id,person_id,address_type,address_name) values(1,1,\'home\',\'xixiang\');
insert into person_address(id,person_id,address_type,address_name) values(3,2,\'home\',\'xixiang\');
insert into person_address(id,person_id,address_type,address_name) values(5,3,\'home\',\'pingzhou\');

insert into person_address(id,person_id,address_type,address_name) values(2,1,\'company\',\'shengtai\');
insert into person_address(id,person_id,address_type,address_name) values(4,2,\'home\',\'changhong\');
insert into person_address(id,person_id,address_type,address_name) values(6,3,\'home\',\'keji\');

insert into person_address(id,person_id,address_type,address_name) values(7,5,\'home\',\'keji\');
select * from person_address

select addre.* from person_base_info per left join person_address addre
on per.id = addre.person_id
where per.id = 1

select * from person_base_info per right join person_address addre
on per.id = addre.person_idl

select * from person_base_info per , person_address addre
where per.id = addre.person_id

 

SqlServer常用字段类型

 

 

int：整型，取值范围[-2³¹~2³¹)

decimal：精确数值型 ，示例：decimal(8,4); //共8位，小数点右4位

money：货币型 

float：近似数值型    

real：近似数值型

varchar：字符型，存储非统一编码型字符数据，数据类型为变长，要指定该列的最大长度，存储的长度不是列长，而是数据的长度 

text：字符型，存储大量的非统一编码型字符数据

datetime：日期时间型，从1753年1月1日到9999年12月31日间所有的日期和时间数据， 精确到三百分之一秒或3.33毫秒  

cursor：特殊数据型，包含一个对游标的引用。用在存储过程中，创建表时不能用 

timestamp：特殊数据型，用来创建一个数据库范围内的唯一数码， 一个表中只能有一个timestamp列，每次插入或修改一行时，timestamp列的值都会改变。

 

 

 

SQLServer （多表左连接，指定操作某几行）

 

SELECT *

  FROM 表1

  LEFT JOIN 表2

    ON 表1.关联字段=表2.关联字段

  LEFT JOIN 表3

    ON (表1/表2).关联字段=表3.关联字段

 WHERE 条件