postgres常用操作

create table region(
    id serial PRIMARY KEY,
    name character varying(128),
    value smallint default 8
);

#会自动创建 region_seq_id表,drop表region时，会自动将region_seq_id表drop

# 删除表中的所有行,并使主键重新计数
truncate region restart identity;

# 或者设置下一条sql插入时的技术起始值
select setval(‘region_seq_id‘, 1, false)

create table user (
    id serial primary key,
    reg_id integer references region(id),
    name character varying(128)    
);

# 或者
create table user (
    id serial primary key,
    reg_id integer,
    name character varying(128),
    forien key(reg_id) references region(id)
);

# 添加列
alter table region add column description text;

# 移除列
alter table region drop column description text;

# 修改列上的默认值
alter table region alter column value set default 0;

# 移除列的默认值
alter table region alter column value drop default;

# 修改列的数据类型
alter table region alter column value type interger;

# 列重命名
alter table region rename column value to region_time;

# 表重命名
alter table region rename to region_time;