在QA里执行sp_attach_db或者sp_attach_single_file_db,出现提示:错误1813:未能打开新数据库dbname,create database 将终止。设备激活错误。物理文件名d:sql servermssqldatadbname _log.ldf可能有误! 后来到baidu里找到相关的方法,不错,问题解决了。 按
在QA里执行sp_attach_db或者sp_attach_single_file_db,出现提示:错误1813:未能打开新数据库’dbname’,create database 将终止。设备激活错误。物理文件名’d:sql servermssqldatadbname _log.ldf’可能有误!
后来到baidu里找到相关的方法,不错,问题解决了。
按下面的步骤处理:
1.新建一个同名的数据库2.再停掉sqlserver服务(注意不要分离数据库)
3.用原数据库的数据文件覆盖掉这个新建的数据库4.再重启sqlserver服务
5.此时打开企业管理器时会出现置疑,先不管,,执行下面的语句(注意修改其中的数据库名)6.完成后一般就可以访问数据库中的数据了。这时,数据库本身一般还有问题,解决办法是:利用数据库的脚本创建一个新的数据库,然后通过DTS将数据导进去就行了
use master
go
sp_configure ’allow updates’,1 reconfigure with override
go
update sysdatabases set status =32768 where name=’置疑的数据库名’
go
sp_dboption ’置疑的数据库名’, ’single user’, ’true’
go
dbcc checkdb(’置疑的数据库名’)
go
update sysdatabases set status =28 where name=’置疑的数据库名’
go
sp_configure ’allow updates’, 0 reconfigure with override
go
sp_dboption ’置疑的数据库名’, ’single user’, ’false’
go

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TocreateanindexinMySQL,usetheCREATEINDEXstatement.1)Forasinglecolumn,use"CREATEINDEXidx_lastnameONemployees(lastname);"2)Foracompositeindex,use"CREATEINDEXidx_nameONemployees(lastname,firstname);"3)Forauniqueindex,use"CREATEU

The main difference between MySQL and SQLite is the design concept and usage scenarios: 1. MySQL is suitable for large applications and enterprise-level solutions, supporting high performance and high concurrency; 2. SQLite is suitable for mobile applications and desktop software, lightweight and easy to embed.

Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.


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