Oracle数据库开发必备利器之SQL基础_技术问答

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Oracle数据库开发必备利器之SQL基础

                
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Oracle数据库开发利器之函数
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dyechen

select * from users;
select id,username,salary+200 from users;
select * from users;

select username from users where salary>800;

select username from users where salary>800 and salary<>1800.5;
select username form users where salary>800 or salary<>1800.5;

0 6-7 Oracle 在select语句中使用运算符

2018-01-10

dyechen

select id as 编号,username as 用户名,salary 工资 from users;
select distinct username as 用户名 from users;

0 6-5 Oracle查询语句之给字段设置别名

2018-01-10

dyechen

select * from users;
col id heading 编号;
col username heading 用户名;
col salary heading 工资;
select * from users;
select username,salary from users;

0 6-4 Oracle查询语句之查询表中的所有字段及指定字段

2018-01-10

dyechen

col username heading 用户名;
select * from users;
col username format a10;
select * from users;
col salary format 9999.9;
select * from users;
col salary format 999.9;
select * from users;
col salary format $9999.9;
select * from users;
col username clear;
col salary clear;
select * from users;

2 6-3 Oracle查询语句之在sql/plus中设置格式

2018-01-10

dyechen

alter table userinfo_c3 drop constraint ck_salary_new;

0 5-14 Oracle 删除检查约束

2018-01-09

dyechen

desc salary
select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_C3';
alter table userinfo_c3 disable constraint ck_salay_new;
select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_C3';

0 5-14 Oracle 删除检查约束

2018-01-09

dyechen

create table userinfo_c3(id varchar2(10) primary key, username varchar2(20), salary number(5,0));
alter table userinfo_c3 add constraint ck_salary_new check(salary>0);

0 5-13 Oracle 在修改表时添加检查约束

2018-01-09

dyechen

create table userinfo_c1(id varchar2(10) primary key,username varchar2(20), salary number(5,0),constraint ck_salary chack(salary>0));

0 5-12 Oracle 在创建表时设置检查约束

2018-01-09

dyechen

create table userinfo_c(id varvhar2(10) primary key, username varchar2(20), salary number(5,0) check(salary>0));
insert into userinfo_c values(1,'aa,-50);

0 5-12 Oracle 在创建表时设置检查约束

2018-01-09

dyechen

alter table userinfo_u2 drop constraint un_username_new;

0 5-11 Oracle 删除唯一约束

2018-01-09

dyechen

select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_U2';
alter table userinfo_u2 disable constraint un_username_new;
select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_U2';

0 5-11 Oracle 删除唯一约束

2018-01-09

dyechen

create table userinfo_u2(id varchar2(10) primary key,username varchar2(20));
alter table userinfo_u2 add constraint un_username_new unique(username);

0 5-10 Oracle 在修改表时添加唯一约束

2018-01-09

dyechen

create table userinfo_u(id varchar2(10) primary key,username varchar2(20) unique,userpwd varchar2(20));
create table userinfo_u1(id varchar2(10) primary key,username varchar(20),userpwd varchar2(20) ,constrait un_username unique(username));

0 5-9 Oracle 在创建表时设置唯一约束

2018-01-09

dyechen

alter table userinfo_f4 drop constraint fk_typeid_alter;
select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_F4';

1 5-8 Oracle 删除约束

2018-01-09

dyechen

select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_F4';
alter table userinfo_f4 fisable constraint fk_typeid_alter;
select constraint_name,constraint_type,status from user_constraints where table_name='USERINFO_F4';

0 5-8 Oracle 删除约束

2018-01-09

dyechen

create table userinfo_f4(id varchar2(10) primary key,username varchar2(20),typeid_new varchar2(10));
alter table userinfo_f4 add constraint fk_typeid_alter foreign key(typeid_new) references typeinfo(typeid);

0 5-7 Oracle 在修改表时添加外键约束

2018-01-09

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Oracle数据库开发必备利器之SQL基础