Oracle 基础（2）——创建表单

创建表单

oracle中的数据类型

number(n) 数字( 最长n位 )

number(n , m) 浮点数( 总长n为, 小数点后m位 )

char(n)表示定长字符串

varchar(n)表示变长字符串( 节省空间 ) 

varchar2(n)Oracle自己定义的变长字符串

date 日期

 

创建一个简单的数据表

CREATETABLE dept_xxx(

deptnoNUMBER(2) primary key,

dname VARCHAR2(30) not null,//not null设置为非空

//dname VARCHAR2(30) constraint student_name_nn not null,设置别名

dlocationVARCHAR2(30),

);

 

CREATETABLE dept_xxx(

deptnoNUMBER(2),

dnameVARCHAR2(30),

dlocationVARCHAR2(30),

constraintdept_xxx_deptno_pk primary key (deptno));

//设置主键名dept_xxx_deptno_pk 主键为deptno （主键可以设计多行）

 

添加Uk唯一约束

create tableuk_table (

num NUMBER(2),

email varchar2(30)UNIQUE);

create tableuk_table (

num NUMBER(2),

email varchar2(30),

constraintuk_table_email_uk unique(email));

 

 

添加Check约束

create tablecheck_table(

sex char(1),

constraintcheack_table_ck CHECK( sex in('f','m')));

 

添加Pk外键约束

专业表

create table major(

id number(2),

name varchar2(20),

constraintmajor_id_pk primary key(id));

学生表

CREATE tablestudent(

id number (2),

name varchar2(20),

major_id number(2),

constraintstudent_id_pk primary key(id),

constraintmajor_student_majorid_fk foreign key (major_id) references major(id) on delete set null);

设置外键，外键为major_id主键为major的id ，当主键表中删除是，外键表设置为null（级联修改）

创建一个较为全面的关系表（事例）

CREATE TABLE student(

s_numVARCHAR2 (12),

major_numNUMBER (2),

s_nameVARCHAR2 (12),

s_sexCHAR (1),

heightNUMBER (3),

weightNUMBER (3),

birthdayDATE,

native_placeVARCHAR2 (20),

CONSTRAINTstudent_num_pk PRIMARY KEY (s_num),

CONSTRAINT major_student_major_num_fk foreign KEY(major_num) REFERENCEs major(major_num),

CONSTRAINTstudent_check_sex_ck CHECK (LOWER(s_sex) IN('f', 'm')),

CONSTRAINTstudent_check_height_ck CHECK (height > 0),

CONSTRAINTstudent_check_weight_ck CHECK (weight > 0),

CONSTRAINTstudent_check_birthday_ck CHECK (

birthday> "TO_DATE" ('1950-01-01', 'yyyy-MM-dd')

ANDbirthday < "SYSDATE"

)

);

 

CREATE TABLE course(

c_numCHAR (6),

major_numNUMBER (2),

c_nameVARCHAR2 (20),

typeNUMBER (1),

creditNUMBER (2),

CONSTRAINTcourse_num_pk PRIMARY KEY (c_num),

CONSTRAINT major_course_major_num_fk foreign KEY(major_num) REFERENCEs major(major_num),

CONSTRAINTcourse_check_type_ck CHECK ("type" IN(1,2,3)),

CONSTRAINTcourse_check_height_ck CHECK ("credit" > 0 and "credit"<= 0)

);

 

CREATE TABLEcourse_tm (

tm_numCHAR (6),

c_numCHAR (6),

constraintcourse_tm_num_pk primary key (tm_num,c_num),

CONSTRAINTcourse_course_tm_c_num_fk foreign KEY (c_num) REFERENCEs course(c_num),

CONSTRAINTteacher_course_tm_tm_num_fk foreign KEY (tm_num) REFERENCEsteaching_material(tm_num)

);