今天在MySQL中建表,一开始在MySQL Query Browser里建,可是总是报错,后来想想,这是只是一个方便操作的客户端软件,估计不行。
今天在MySQL中建表,一开始在MySQL Query Browser里建,可是总是报错,后来想想,这是只是一个方便操作的客户端软件,估计不行。后来又在服务器端管理软件MySQL Administrator下建表,可是还是出现同样的错误。没办法只好上网求助了。
一查原来才知道,在MySQL中建表大多数情况下是在DOS命令行下创建的。进入命令行后首先输入:net start MySQL (停止服务器用:net stop MySQL)服务器启动好后再输入:MySQL -uroot -p 这里的root代表用户名。按回车后将提示你输入密码:Enter password:密码就是安装的时候设置的密码。(在这一步可能出现MySQL不是内部命令的提示,那是因为环境变量没设置,应该把MySQL安装目录 下的bin目录添加到path中去,比如我的是D:\program files\MySQL\bin)当出项MySQL>的提示时就可以建表了。比如要在test中建立guestbook表,步骤如下: MySQL> use test Database changed MySQL>create table guestbook ->( ->serial_no int auto_increment not null primary key, ->name varchar(10) not null, ->guest_time varchar(10) not null ->); 这样一个表就创建成功了,不过在输入过程中要注意not null前要有个空格,还有就是逗号不要丢了,最后一行后没有逗号以及)后的";"号,这些都是数据库的基本知识,,可是我忘了,以至于建了好几次才成功。

ACID attributes include atomicity, consistency, isolation and durability, and are the cornerstone of database design. 1. Atomicity ensures that the transaction is either completely successful or completely failed. 2. Consistency ensures that the database remains consistent before and after a transaction. 3. Isolation ensures that transactions do not interfere with each other. 4. Persistence ensures that data is permanently saved after transaction submission.

MySQL is not only a database management system (DBMS) but also closely related to programming languages. 1) As a DBMS, MySQL is used to store, organize and retrieve data, and optimizing indexes can improve query performance. 2) Combining SQL with programming languages, embedded in Python, using ORM tools such as SQLAlchemy can simplify operations. 3) Performance optimization includes indexing, querying, caching, library and table division and transaction management.

MySQL uses SQL commands to manage data. 1. Basic commands include SELECT, INSERT, UPDATE and DELETE. 2. Advanced usage involves JOIN, subquery and aggregate functions. 3. Common errors include syntax, logic and performance issues. 4. Optimization tips include using indexes, avoiding SELECT* and using LIMIT.

MySQL is an efficient relational database management system suitable for storing and managing data. Its advantages include high-performance queries, flexible transaction processing and rich data types. In practical applications, MySQL is often used in e-commerce platforms, social networks and content management systems, but attention should be paid to performance optimization, data security and scalability.

The relationship between SQL and MySQL is the relationship between standard languages and specific implementations. 1.SQL is a standard language used to manage and operate relational databases, allowing data addition, deletion, modification and query. 2.MySQL is a specific database management system that uses SQL as its operating language and provides efficient data storage and management.

InnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.

Key metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.

Usingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB


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