CREATE TABLE parent ( id NUMBER PRIMARY KEY ); CREATE TABLE child ( id NUMBER, parent_id NUMBER, FOREIGN KEY (parent_id) REFERENCES parent(id) ON DELETE CASCADE ); 复制代码 级联更新(ON UPDATE CASCADE):当更新一个表中的主键值时,与之相关的所有外键值也将在其他表中更新。 CREATE TABLE parent...
name varchar2(20)); –给t3表加入外键约束 – SQL> alter table t3 add constraint FK_PRODUCTSTAT_PRODUCTID foreign key (PRODUCT_id) references t2 (ID) ON DELETE CASCADE ; 插入表数据 SQL> insert into t2 values(1,‘dh’); SQL>
在SQL Server 中有5 种约束:主关键字约束(Primary Key Constraint)、外关键字约束(Foreign Key Constraint)、惟一性约束(Unique Constraint)、检查约束(Check Constraint)和缺省约束(Default Constraint)。 1 主关键字约束 主关键字约束指定表的一列或几列的组合的值在表中具有惟一性,即能惟一地指定一行记录。每个表...
createorreplaceprocedureChangeStuId(S#_oldininteger, S#_newininteger)asbeginexecuteimmediate'alter table SC disable constraint sidfk';updateStudentsetS#=S#_newwhereS#=S#_old;updateSCsetS#=S#_newwhereS#=S#_old;executeimmediate'alter table SC enable constraint sidfk';end;...
?七、约束(constraint) ?7.1 主键约束(primary key) ?7.2 唯一约束(unique) ?7.3 检查约束(check) ?7.4 默认值约束(default) ?7.5 非空约束(not null) ?八、索引(index) ?九、序列(sequence) ?十、视图(view) ?10.1 创建视图 ?10.2 视图查询
SQL> set constraint pk immediate; set constraint pk immediate * ERROR at line 1: ORA-02447: cannot defer a constraint that is not deferrable --增加一个uk,指定deferrable initially immidiate|deferred SQL> alter table aa add constraint uk unique (name) deferrable initially immediate; ...
SQL>alter table dept2 modify constraint dept2_u1 enable novalidate; alter table dept2 modify constraint dept2_u1 enable novalidate ORA-02299: cannot validate (SYSTEM.DEPT2_U1) - duplicate keys found (因为enable会去创建唯一性索引,而已有数据deptno存在重复数据10,所以这里不能enable) ...
SET CONSTRAINT(s) unq_num/all deferred; 停用: ALTER TABLE dept DISABLE CONSTRAINT dname_ukey; ALTER TABLE dept DISABLE PRIMARY KEY KEEP INDEX, DISABLE UNIQUE (dname, loc) KEEP INDEX; 启用非校验: ALTER TABLE dept ENABLE CONSTRAINT dname_ukey; ...
select 'ALTER TABLE ' || TABLE_NAME || ' drop CONSTRAINT ' ||constraint_name || '; ' as v_sqlfrom user_constraintswhere CONSTRAINT_TYPE in ('R' ) andowner = 'ARTISAN'and upper(table_name) in ('TB_ARTSIAN_ATTR')union allselect 'ALTER TABLE ' || a.TABLE_NAME || ' drop CONST...
WHEN DUP_VAL_ON_INDEX THEN -- 处理唯一约束冲突,例如更新现有记录或记录日志 UPDATE your_table SET other_column = 'new_value' WHERE unique_column = 'value'; END; 通过上述方法,可以有效地解决生产环境中Oracle报ORA-00001: unique constraint的问题。简道云是一款可以帮助企业实现数据管理和流程自动化的工...