String Post_Code = "CREATE TABLE IF NOT EXISTS PostCode(" + "PostCode_ID integer PRIMARY KEY, " + "Code string NOT NULL, " + "City_ID integer," + "FOREIGN KEY (City_ID)" + "REFERENCES City (City_ID)" + "ON UPDATE CASCADE " + "ON DELETE SET NULL, " + "County_ID integer,...
[CONSTRAINT] [外键约束名称] FOREIGN KEY(外键字段名) REFERENCES 主表名(主键字 段名) 2. 已有表添加外键 ALTER TABLE 从表 ADD [CONSTRAINT] [外键约束名称] FOREIGN KEY (外键字段名) REFERENCES 主表(主键字段名); */ -- 创建主表 create table department( id INT PRIMARY KEY auto_increment, dep_...
sqlite>sqlite>CREATE TABLE Teachers(Id integer PRIMARY KEY,Name text);sqlite>.tablesTeacherssqlite>INSERT INTO Teachers(Name) Values('张三');sqlite>INSERT INTO Teachers(Name) Values('李四');sqlite>INSERT INTO Teachers(Name) Values('王二麻子');sqlite>SELECT * FROM Teachers;Id Name--- ---1 ...
dos窗口启动cmd MySQL -u root{默认账户} -p 显示输入密码没有密码直接回车 创建数据库:create database 名字; 查看数据库:show databases; 创建表:CREATE TABLE s(id INT(50),NAME VARCHAR(50),sex CHAR(2),birthday DATETIME); date(精确到年月日)datetime(精确到年月日时分秒) 删除表:drop table custom...
sqlite>sqlite>.tablesTeacherssqlite>CREATE TABLE Students (Id integer PRIMARY KEY, TeacherId integer,FOREIGN KEY(TeacherId) REFERENCES Teachers(id));sqlite>.tablesStudents Teacherssqlite>SELECT * FROM Teachers;Id Age --- --- 1 40 2 33 3 23sqlite...
全外连接select * from Afull outer join Bon A.key = B.key;不支持。用左外连接、右外连接,合并剔重后实现。 select * from Afull outer join Bon A.key = B.keywhere A.key is NULLor B.key is NULL; 自然连接实例: CREATE TABLE A (B VARCHAR(20), C integer);CREATE TABLE B (B VARCHAR...
Name CREATE TABLE — Define and create a new table Syntax column-def: type-name: column-constraint: table-constraint: foreign-key-clause: conflict-clause: Common Usage CREATE TABLE database_name.table_name ( c1_name c1_type, c2_name c2_type... … - Sele
创建包含递归外键的表:CREATE TABLE employees ( id INTEGER PRIMARY KEY, name TEXT, manager_id INTEGER, FOREIGN KEY(manager_id) REFERENCES employees(id) ); 插入数据:INSERT INTO employees (id, name, manager_id) VALUES (1, 'John', NULL); INSERT INTO employees (id, name, manager_id) VALUES...
foreign key constraint fails错误的原因 2015-11-07 11:10 −建表:CREATE TABLE Course ( Cno Char(4) PRIMARY KEY, Cname Char(40), Cpno Char(4), Ccredit Int, FOREIGN KEY (Cpno) REFERENCES Course(Cno) );插入数据:INSE... BestWangJie ...
foreign key - 外键 check - 条件检查,确保一列中的所有值满足一定条件 default - 默认 autoincreatement - 自增型变量 SQL语句 SQL的语句我们可以分成两个部分来看,分别是:数据操作语言(DML)和数据定义语言(DDL) 查询和更新指令构成了SQL的DML部分: