Every movie needs a director and every rented movie needs to exist in the store. How do we make sure something in another table exists before inserting new data? This lesson will teach us about foreign keys and references. CREATE TABLE directors ( id…

在数据库里面使用TRUNCATE命令截断一个表的数据时,遇到如下错误 SQL >TRUNCATE TABLE ESCMOWNER.SUBX_ITEM ORA-02266: unique/primary keys in table referenced by enabled foreign keys 有时候对应的中文错误提示为:ORA-02266: 表中的唯一/主键被启用的外部关键字引用,一般出现这个错误,是因为表中的主键被其它表的外键所引用,导致删除数据时出错. 此时,你可以通过下面脚本查看一下…

对称/非对称/混合加密的冷知识 数据在互联网上传输,要考虑安全性. 讲到安全,要从三方面考虑: 1.authentication 每一个IP包的认证,确保合法源的数据 2.data integrity 验证数据完整性,保证在传输过程中没有被人为改动 3.confidentiality (私密性)数据包的加密 下面谈谈如何对数据加密. 于是有了非对称加密 对称加密 对称加密算法---使用一把密匙来对信息提供安全的保护.只有一个密匙,即用来加密,也用来解密 特点: - 1.速度快 - 2.密文紧凑…

How can I list all foreign keys referencing a given table in SQL Server?  how to check if columns in table was used as foreign key in other tables   Not sure why no one suggested but I use sp_fkeys to query foreign keys for a given table: EXEC sp_fke…

关于ORA-02273错误,以前还真没有仔细留意过.昨天遇到了这个问题,遂顺便总结一番,以后遇到这类问题就可以直接用下面方案解决.如下所示,我们首先准备一下测试环境. CREATE TABLE TEST.TEST (  OWNER            VARCHAR2(30),    OBJECT_ID        NUMBER,    OBJECT_NAME      VARCHAR2(30) );   CREATE INDEX TEST.IX_TEST_N1 ON TEST.TEST(O…

使用 PGO 在 Kubernetes 上运行 Cloud Native PostgreSQL:来自 Crunchy Data 的 Postgres Operator! Cloud Native PostgreSQL https://www.crunchydata.com/products/crunchy-postgresql-for-kubernetes/ Crunchy Data https://www.crunchydata.com/ Postgres Operator https://g…

因数据库存储数据要持之以恒,数据库中的表需要一些方法验证各种数据类型.不仅仅局限于数据类型,还有唯一值,值的范围,或者某列的值和另外一个表中的列匹配. 当你在定义表的时候其用这些数据验证方法.这叫做声明数据完整性.也就是我们说的表约束. USE tempdb GO CREATE TABLE s ( sid ) , sname ) , ssex ) CHECK ( ssex = '男' OR ssex = '女' ) DEFAULT '男' , sage ) , sclass ) UNIQUE ,…

https://docs.microsoft.com/en-us/sql/relational-databases/tables/create-foreign-key-relationships?view=sql-server-2017 Create a foreign key relationship in Table Designer Create a foreign key relationship in Table Designer Using SQL Server Management…

本文转自:https://stackoverflow.com/questions/483193/how-can-i-list-all-foreign-keys-referencing-a-given-table-in-sql-server EXEC sp_fkeys 'TableName' SELECT    'ALTER TABLE ['+sch.name+'].['+referencingTable.Name+'] DROP CONSTRAINT ['+foreignKey.name+']'…

down voteaccepted For a Table: SELECT TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_SCHEMA = '<database>' AND REFERENCED_TABLE_NAME = '<table&g…