SQL> alter table emp add constraint emp_deptno_fk foreign key(deptno) references dept(deptno) on delete set null; 实际上,外键约束列和对应的父表列可以在同一张表中,常见的就是表的业务逻辑含义是一棵树,最简单的例子如下(id为主键id,fid为父id,fid存储对id的引用),这种结构的表根据业务要求可通过Ora...
SQL>altertableempaddconstraintemp_deptno_fkforeignkey(deptno)referencesdept(deptno)ondeletesetnull; 实际上,外键约束列和对应的父表列可以在同一张表中,常见的就是表的业务逻辑含义是一棵树,最简单的例子如下(id为主键id,fid为父id,fid存储对id的引用),这种结构的表根据业务要求可通过Oracle的递归查询来获取这种...
SQL>altertableempaddconstraintemp_deptno_fkforeignkey(deptno)referencesdept(deptno)ondeletesetnull; 实际上,外键约束列和对应的父表列可以在同一张表中,常见的就是表的业务逻辑含义是一棵树,最简单的例子如下(id为主键id,fid为父id,fid存储对id的引用),这种结构的表根据业务要求可通过Oracle的递归查询来获取这种...
EDIT: @Allan's answer is a good one, but I am concerned (in my lack of Oracle expertise) that it may not be universally true that any constraint that might have a system-generated name will have associated with it a way to remove the constraint without having to...
Theemp_email_uk constraint ensures that no two employees have the same emailaddress, as shown in Example5-1. Example 5-1 Unique Constraint SQL> SELECT employee_id, last_name,email FROM employees WHERE email = 'PFAY'; ...
后台服务测试过程中,发现往oracle数据库表中插数据出现一个错误 unique constraint 如下: Error updating database. Cause: java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (TEST53.SYS_C0032604) violated The error may exist in class path resource [sqlmapper/ACMClaimMapper.xml...
SQLスクリプトの詳細は、『Oracle Database PL/SQLパッケージおよびタイプ・リファレンス』のDBMS_IOTパッケージを参照してください。 移行行および連鎖行の削除については、『Oracle Databaseパフォーマンス・チューニング・ガイド』を参照してください。 ビュー制約 Oracleでは、ビュ...
to create the index and use it to enforce the constraint. If Oracle cannot create the index or cannot use the index to enforce the constraint, then Oracle returns an error.If you neither specify an existing index nor create a new index, then Oracle creates the index. In this ...
1 Using sql oracle to add a foreign key 177 Add new column with foreign key constraint in one command 0 Add Foreign Key to an existing column? 0 How to add unique constraint as foreign key ? 1 Oracle SQL add foreign key 2 Modifying an existing column to a...
思路 在Oracle 中,可以使用以下方法找出重复的主键: 使用GROUP BY 和 HAVING 子句:使用 GROUP BY 子句按照主键列进行分组,并使用 HAVING 子句筛选出出现次数大于 1 的主键。 代码语言:javascript 复制 sqlSELECT primary_key_column,COUNT(*)FROMtable_nameGROUPBYprimary_key_columnHAVINGCOUNT(*)>1; ...