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)
);