解决SQL Server的“此数据库没有有效所有者”问题,需要的朋友可以参考下。
在附加数据库后查看不了数据库关系图,也无法建立数据库关系图我的解决方法如下:
1、设置兼容级别为90(2005为90)(2000为80)
代码如下:
USE [master]
GO
EXEC dbo.sp_dbcmptlevel @dbname='数据库名', @new_cmptlevel=90
GO
[这条命令执行完毕:报“DBCC 执行完毕。如果 DBCC 输出了错误信息,请与系统管理员联系”,不管它哦,接下来点击“数据库关系图”,报“此数据库缺少一个或多个使用数据库关系图所需的支持对象,是否创建”,选择“是”,问题解决了]
或是选择你还原的数据库,点右键,选属性->选项->兼容级别,选择sqlserver2005(90) 然后确定。
这时,你在该数据库下展开“数据库关系图”节点时会有个提示,"此数据库缺少一个或多个使用数据库关系图所需的支持对象,是否创建",选择“是”即可。
2、通过以上的方法操作,如果问题依然存在的话,按下列方法继续
选择你的数据库,然后选择"安全性"->"用户",选择dbo,打开属性页,如登录名为空的话,新建查询,然后
代码如下:
use [你的数据库名]
EXEC sp_changedbowner 'sa'
执行成功后,你再选择"数据库关系图"节点,时提示 “此数据库缺少一个或多个使用数据库关系图所需的支持对象,是否创建",选择“是”即可。 就可以看到原先建的关系图了。

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MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

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SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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