1、Primary Key约束 SQLServer 中有五种约束, Primary Key 约束、 Foreign Key 约束、 Unique 约束、 Default 约束和 Check 约束. 在表中常有一列或多列的组合,其值能唯一标识表中的每一行。 这样的一列或多列成为表的主键(PrimaryKey)。一个表只能有一个主键,而且主键约束中的列不能为空值。只有主键列才能...
The primary key in the Customers table is CustomerNo, and the primary key in the Orders table is OrderNo. The primary key uniquely identifies the table and contains the value that the foreign key refers to. Primary keys must be unique to each row of data. In the Orders table, the Custo...
I made a unique key out of two columns to use as my primary key. I want one of the columns to be a foreign key as well, but I get an error when I try to do that. I have a table (drawing) that stores drawings with the primary key dwgID. I want to make a table (drawingrev...
ALTER TABLE TEST.RF_TEST ADD CONSTRAINT PK_RF_TEST PRIMARY KEY(ID) USING INDEX TABLESPACE TEST_DATA; 1. 1. ALTER TABLE TEST.RF_TEST ADD CONSTRAINT FK_RF_TEST FOREIGN KEY(OBJECT_ID ) REFERENCES TEST.TEST(OBJECT_ID); 1. 如下所示,由于脚本上面的原因(没有指定主键约束对应的索引,而且又有其...
ORA-02273: this unique/primary key is referenced by some foreign keys.. Answer/guest Cause: Self-evident. Action: Remove all references to the key before the key is to be dropped. Please add more information about this Error Is This Answer Correct ?2 Yes1 No ...
MySQL requires only that the column be indexed, and SQLite has no requirements (it does not enforce foreign key constraints). Django requires uniqueness so it should be enforcing this on its own. The documentation of to_field should also specify that it should be unique. Here is the relevant...
(fid) REFERENCES t1 (id)); sqlite> .indices t1 sqlite_autoindex_t1_1 sqlite> .indices t2 sqlite_autoindex_t2_1 sqlite> insert into t1 values (1,'test'); sqlite> insert into t2 values (1, 1,'test'); sqlite> insert into t2 values (1, 99,'test'); Error: UNIQUE constraint failed...
CREATETABLEt_employee( emp_idINT(3)PRIMARYKEY, emp_noINT(3)UNIQUENOTNULL, emp_nameVARCHAR(10)NOTNULL, emp_agetinyint(4)NOTNULLDEFAULT25CHECK(emp_ageBETWEEN20AND60), sexVARCHAR(1)CHECK(sexin('男','女')), jobVARCHAR(20), salINT(10),--inline写法--REFERENCES 主表(主表字段)--dept_no...
--remap-column can be employed to handle cases in which primary and unique key values are overlapping between source clusters, and it is necessary that they do not overlap in the target cluster, as well as to preserve other relationships between tables such as foreign keys. --remap-column ...
Okay, I'm stupid, lol. The reason I couldn't create the foreign key had nothing to do with my unique index. It was because I had data in my drawingrev table (to test the unique index) even tho no data yet existed in my drawing table. So the dwgID I was trying to make my for...