ALTER TABLE orders ADD CONSTRAINT fk_customer FOREIGN KEY (customer_id) REFERENCES customers(id); 在这个例子中,fk_customer是外键约束的名称,customer_id是orders表中的外键列,它引用了customers表的id列。 3. 执行SQL语句以在数据库中创建外键 执行上述SQL语句后,PostgreSQL数据库将创建相应的外键约束。你可...
constraint student_table3_ibfk_1 foreign key(java_teacher_name,java_teacher_pass) references teacher_table3(teacher_name,teacher_pass) ); #删除foreign key alter table student_table3 drop foreign key student_table3_ibfk_1; #修改表结构时增加foreign key alter table student_table3 add foreign key...
3,增加约束 ALTER TABLE products ADD CHECK (name <> ''); ALTER TABLE products ADD CONSTRAINT some_name UNIQUE (product_no); ALTER TABLE products ADD FOREIGN KEY (product_group_id) REFERENCES product_groups; 要增加一个不能写成表约束的非空约束,使用下面语法: ALTER TABLE products ALTER COLUMN p...
(1)、 添加主键 altertablegoodsaddprimarykey(sid); AI代码助手复制代码 (2)、 添加外键 altertableordersaddforeignkey(goods_id)referencesgoods(sid)onupdatecascadeondeletecascade; AI代码助手复制代码 on update cascade:被引用行更新时,引用行自动更新; on update restrict:被引用的行禁止更新; on delete casca...
foreign key("UserId") references "SysUser"("UserId") ); --说明:外键默认名称为tablename_columnname_fkey 1. 2. 3. 4. 5. 6. 7. 8. 9. 3.通过修改表结构设置外键 --语法:alter table table_name add [constraint constraint_name] foreign key(column_1) references TableName(ColumnName); ...
增加一列ALTERTABLEproductsADDCOLUMNdescriptiontext;ALTERTABLEproductsADDCOLUMNdescriptiontextCHECK(description<>''); 提示: 增加一个带默认值的列需要更新表中的每一行(来存储新列值)。然而,如果不指定默认值,PostgreSQL可以避免物理更新。因此如果我们准备向列中填充的值大多是非默认值,最好是增加列的时候不指定默认...
SQL state: 23503 错误通常表示违反了外键约束。这意味着你尝试添加的约束与表中已存在的数据不兼容。具体来说,当你尝试添加一个外键约束时,PostgreSQL会检查引用的表中是否存在对应的主键值。如果不存在,就会抛出这个错误。 基础概念 外键约束(Foreign Key Constraint)用于确保一个表...
postgreSQL数据库默认⽤户postgres常⽤命令分享 1、修改⽤户postgres的密码 #alter user postgres with password ‘xxxx';(其中xxxx是修改的密码)。2、查看下当前schema的所有者：// 查看当前schema的所有者，相当于\du元命令 SELECT n.nspname AS "Name",pg_catalog.pg_get_userbyid(n.nspowner) AS "...
> ALTER TABLE menu add foreign key (menu_id_father) > references menu ( menu_id); > > error: Can't create table > './proyect3/#sql-3db_36.frm' (errno: 150) > > -- trying this: > > CREATE TABLE menu ( > menu_id int auto_increment primary key, foreign ...
ADD FOREIGN KEY — Isn't supported if current user doesn't have permission to read the referenced table or if the referenced table has RLS restrictions enabled that the current user can't bypass. The following example fails because it tries to add a constant value of type timestamp onto a...