Mysql Max Id

MySQL optimization is very important. The most common and most needed optimization is limit. 　　The limit of MySQL brings great convenience to paging, but when the amount of data is large, the performance of limit is reduced dramatically. The same is 10 data select * FROM Yanxue8_visit limit 10000,10 and select * from Yanxue8_visit limit 0,10 is not a quantitative level ...

Generally come out forget the password is a new MySQL novice friend, below we tell you how to use mysqadmin to change the password to come. I'll take a few examples and I'm sure I'll see. 1, the original password is 123456 c:>type mysql5.bat @echo off mysql-uroot-p123456-p3306 correct changes to the MySQL user password format is: We use the User: root (can be replaced by other) Password: WoS ...

A few days, in the management of the system encountered a strange problem, today have the opportunity to install the MySQL environment to reproduce the problem, because it is not the most primitive environment, so may not be able to fully reproduce, I can only try to reproduce the key The problem .. I think this issue is a bit special, so in this probably recall the scene under the circumstances .. Work, the implementation of a su & ndash; mysql command, encountered such an error .. view sourceprint? 1 [root @dbmain ~ ...

Mysql limit usage: When we use the query, often to return to the first few or a few lines in the middle of the data, how to do this time? Do not worry, mysql has provided us with such a function. SELECT * FROM table LIMIT [offset,] rows | rows OFFSET & nbs ...

select * from table limit [offset,] rows | rows offset The offset clause clause can be used to force a select statement to return the specified number of records. limit Accepts one or two numeric parameters. The parameter must be an integer constant. Given two parameters, the first parameter specifies the offset of the first record row, and the second parameter specifies the maximum number of record rows to return. The offset of the initial record line is 0 (not 1): ...

In our development of the efficiency has been a problem, especially for a lot of large data operations, today we ran into a random query data, at first we may think of the simplest order by RAND () to operate but the efficiency is not flattering ah. Recently, because of the need to study the MySQL random extraction implementation method. For example, to randomly extract a record from the TableName table, the general wording is: SELECT * from TableName ORDER by RAND () LIM ...

Recently due to the need to study about MYSQL based random extraction method. For example, to randomly extract a record from the table table, we generally write: SELECT * FROM tablename ORDER BY RAND () LIMIT 1. However, I checked the official MYSQL manual, which prompts for RAND () probably means that the ORDER BY clause can not be used inside the RAND () function, because this will lead to multiple data columns were swept ...

In MySQL, using the id field of the auto_increment type as the primary key of a table and using it as a foreign key to other tables to form a "master-slave table structure" is a common usage in database design. However, in the specific generation of id, our order of operations is generally: insert records in the main table, and then get the automatically generated id, based on it to insert the record from the table. There is a difficulty here, is inserted into the main table record, how to get it corresponds to the id. The usual practice is through "select max (id) from table ...

The MySQL tutorial does not use the rand () function to randomly read the database tutorial records, as well as Google the relevant files, found that everyone almost exclusively using ORDER by RAND () to achieve this, but in fact there are very serious performance problems. If your database has only hundreds of, and the number of calls is not many times, you love what method to use what method. But if you have 100,000 or 1 million or more data, then each time you execute the SQL with ORDER by rand () ...

Method 1 delete yourtable where [id] not in (select max ([id]) from yourtable group by (name + value) b on a.id = b.id where b.id ...