在CMD下运行如下命令就可以: lsnrctl status 正在连接到(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=spcc)(PORT=1525))) TNS-12541: TNS:无监听器 TNS-12560: TNS: 协议适配器错误 TNS-00511: 无监听器 32-bit Windows Error: 61: Unknown error 打开监听器
lsnrctl status
正在连接到(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=spcc)(PORT=1525)))
TNS-12541: TNS:无监听器
TNS-12560: TNS: 协议适配器错误
TNS-00511: 无监听器
32-bit Windows Error: 61: Unknown error
打开监听器:
C:\Users\Administrator>LSNRCTL START
LSNRCTL for 32-bit Windows: Version 10.2.0.1.0 - Production on05-11月-2012 15:5
0:53
Copyright (c) 1991, 2005, Oracle.
TNS-01106: 使用名称LISTENER的监听程序已经启动
2.尝试登录本地数据库看是否成功
C:\Users\Administrator>sqlplus /nolog
SQL*Plus: Release 10.2.0.1.0 - Production on 星期一 11月 5 15:53:362012
Copyright (c) 1982, 2005, Oracle.
SQL>
如上所示表示正确连接,且tnsnames.ora文件没有问题,如果连接失败请检查服务是否开启,并且检查tnsnames.ora文件内容是否有误,如下:
orcl =
(DESCRIPTION =
)在orcl前面是不允许出现空格的,并且最好将自己添加的内容放置在原有内容之后。
个人认为上面两项足可以解决该问题了,至于网上其他网友的论述不予评论,本人在检查完上述所有信息后就可以登录了。
这里顺便贴出网友给出的另外的解决方案以便大家参考:
3.如果确保你的tnsnames.ora内容没有错误,那请将%ORACLE_HOME%\product\10.2.0\db_1\NETWORK\ADMIN目录下的所有文件删了,然后重新连接,一般就能解决了。说明一下:那个目录里的文件是在你建立连接的时候动态生成的,不要怕删了会有问题
4.进入PLSQLDeveloper的主界面,在登录界面选择取消即不登录进入主界面,然后选择菜单Tools(工具)-Preferences(首选项),在设置窗口中,选择Oracle-Connection(连接),对应设置窗口中,找到OracleHome(Oracle主目录),选择你本地所安装客户端的版本,保存设置,然后重新启动PLSQLDeveloper,这时就可以正常登录了。
最近买了新电脑,装了64位新系统,突然间又遇到了上面的问题,奇怪了就上面的所有的我都已经验证,到底为什么还是报这个错呢,搞了半天是因为plsql装的位置不对,原来64位win7会把32位应用程序安装到ProgramFiles (x86)目录下,安装的时候我觉得吧这也没什么,结果偏偏是它出问题了,奶奶的,重新装了并且换到C:\ProgramFiles目录下,结果链接正常了,太让人纠结了,还有,为了避免这种问题再度出现,建议oracle客户端也要注意安装路径

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.

SQL commands in MySQL can be divided into categories such as DDL, DML, DQL, DCL, etc., and are used to create, modify, delete databases and tables, insert, update, delete data, and perform complex query operations. 1. Basic usage includes CREATETABLE creation table, INSERTINTO insert data, and SELECT query data. 2. Advanced usage involves JOIN for table joins, subqueries and GROUPBY for data aggregation. 3. Common errors such as syntax errors, data type mismatch and permission problems can be debugged through syntax checking, data type conversion and permission management. 4. Performance optimization suggestions include using indexes, avoiding full table scanning, optimizing JOIN operations and using transactions to ensure data consistency.

InnoDB achieves atomicity through undolog, consistency and isolation through locking mechanism and MVCC, and persistence through redolog. 1) Atomicity: Use undolog to record the original data to ensure that the transaction can be rolled back. 2) Consistency: Ensure the data consistency through row-level locking and MVCC. 3) Isolation: Supports multiple isolation levels, and REPEATABLEREAD is used by default. 4) Persistence: Use redolog to record modifications to ensure that data is saved for a long time.

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

MySQL is suitable for small and large enterprises. 1) Small businesses can use MySQL for basic data management, such as storing customer information. 2) Large enterprises can use MySQL to process massive data and complex business logic to optimize query performance and transaction processing.

InnoDB effectively prevents phantom reading through Next-KeyLocking mechanism. 1) Next-KeyLocking combines row lock and gap lock to lock records and their gaps to prevent new records from being inserted. 2) In practical applications, by optimizing query and adjusting isolation levels, lock competition can be reduced and concurrency performance can be improved.


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