我正在尝试删除当前索引,但仍然收到错误MySQL Cannot drop index needed in a foreignkeyconstraint UNIQUE KEY `AID` (`AID`,`BID`,`CID`), KEY `CID` (`CID`),
CONSTRAINT`mytable_ibfk_1` FOREI
create table artist id int primary key auto_increment, nationalityinto artist (name, nationality) values ('Rush', 'Canadian');
( name varchar (128) not null,
foreignkey(manager_ID) references employee(emp_ID) /*might not be needed*/ constraint Proj_Dep_FK foreignkey (dept_ID) references departmentdept_location_PK p
C时: partner_id INT, total_fund FLOAT, FOREIGNKEY (partners_id) REFERENCES A(partner_id) ON delete SET NULL,FOREIGNKEY (branch_id) REFERENCES B(branch_id) ON d
然而,如果不添加冗余的UNIQUE约束(请参阅下面的代码),我将得到错误:ERROR: there is no unique constraint matching given keys for referencedobjects FOREIGNKEY (root_node) REFERENCES nodes(node_id);
-- Whythis constaint is needed?Since node_id is prim