id int not null primary key, boy_id int not null, girl_id int not null, constraint fk_boy foreign key (boy_id) references boy(id), constraint fk_girl foreign key (girl_id) references girl(id) ); -- 创建表之后添加外键 alter table boy_girl add constraint fk_boy foreign key (boy_i...
ID int identity(1,1) primary key, test002ID int foreign key references test002(ID) ON UPDATE NOT ACTION ON DELETE CASCADE, ,--创建外键 OrderDate datetime default(getdate()), name nvarchar(20) not null )---下面一一介绍。外键ON后面可以跟4个参数。SET NULL,SET DEFAULT,NOT ACTION ,CASCADE...
写法1:test=#createtablecompany(idintprimarykeynotnull,nametextnotnull,ageintnotnull,addresschar(50),salaryreal); 写法2:test=#CREATETABLECOMPANY(test(#IDINTPRIMARYKEYNOTNULL,test(#NAMETEXTNOTNULL,test(#AGEINTNOTNULL,test(#ADDRESSCHAR(50),test(#SALARYREALtest(#);# create tabke company(); 表示...
增加约束ALTERTABLEproductsADDCHECK(name<>'');ALTERTABLEproductsADDCONSTRAINTsome_nameUNIQUE(product_no);ALTERTABLEproductsADDFOREIGNKEY(product_group_id)REFERENCESproduct_groups;ALTERTABLEproductsALTERCOLUMNproduct_noSETNOTNULL; 移除约束,"psql \d 表名"来查看系统默认约束名ALTERTABLEproductsDROPCONSTRAINTsome_n...
The Primary and Foreign Key, Check, Not-Null, and Unique constraints operate similarly in both database systems. IdentifiersOracle converts names of schema, tables, columns, and functions to uppercase unless the name is given in quotes, while Postgres converts them to lowerca...
as: 'services', foreignKey: 'asset_type', onDelete: 'set null', onUpdate: 'set null', hooks: true }); } Services Table: const Service = sequelize.define( 'Service', { id: { type: DataTypes.INTEGER, autoIncrement: true, primaryKey: true ...
where the really large table (clicks) is distributed. Because the Clicks table has a foreign key to Ads, we turn Ads into a reference table. Ads also has foreign keys to other tables, but we can keep those other tables (Campaigns, Publishers, Advertisers) as local table...
SQL级联删除——删除主表同时删除从表——同时删除具有主外键关系的表 create table a ( id varchar(20) primary key, password varchar(20)...userId varchar(20), foreign key (userId) references a(id...
CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 'S' THEN 'sequence' WHEN 'f' THEN 'foreign table' WHEN 'p' THEN 'partitioned table' END as "Type", pg_catalog.array_to_string(c.relacl, E'\n') AS "Access privileges", pg...
set now [database_to_tcl_string $db "select [db_sysdate] from dual"] Dual表 Oracle的SELECT中实际不需要表名的地方可以使用表DUAL,因为Oracle中的FROM子句是必须的。Postgsql中可以将FROM子句丢弃。可以在postgres中创建一个视图作为这个表从而消除上述问题。这样就可以在不干扰Postgres的解析器情况下兼容Oracle...