MySQL

The mysql official website began releasing various versions of the 5.6 series starting in May,. the mysql series versions have been comprehensively refined, the following is a sharing record of the mysql5.6.10 source code installation process

Problem:In Ubuntu, a MySQL account is added,Granted full database operation Permissions,And allow external connections from the databaseHoweverUnable to remotely access MySQL database.Cause:In Ubuntu, the default MySQL installation limits that only

The information_schema database is generated after mysql 5.0. A virtual database does not exist physically.The information_schema database is similar to the "Data Dictionary" and provides a way to access database metadata, that is, Data. For example,

# Path to installation directory. All paths are usually resolved relative to this.Basedir = "D: \ MySQL Server 5.1 /"# Path to the database rootDatadir = "D: \ MySQL Server 5.1/Data /" However, services are not generated because of no installation.

My previous colleagues asked me about the SQL statements in this regard. I remember it specially. After all, this is also quite common.Copy codeThe Code is as follows:Select * from (select * from member_paymentOrder by id desc) t group by member_id

In actual development, you always encounter this situation. Or in this case If you are still using select fields from table where like '/%', it is definitely a thankless practice, taking a closer look at the built-in functions of MYSQL is

In web development, we often need to insert data from a table to another table. Sometimes, we also need to specify the import field to import records that do not exist in the target table, although these can be split into simple SQL statements in

Mysql supports many field types, including numeric, date/time, and string (character). storage space and storage efficiency must be taken into account during use;The following conventions are used for column type descriptions:· MThe maximum display

If you use delayed-insert to insert data, you do not need to lock the table../Bin/mysqldump-uroot-proot -- lock-tables -- extended-insert -- opt -- quick -- master-data test>/home/zhanghong/opdir/tmp/test. SQL--Lock tables 'student 'WRITE;/*! 40000

Backup Data method:I. SQL statements.Locks tables tablename READ; // READ lockBefore trying to LOCK a table, lock tables is not TRANSACTION-safe. It implicitly commits all active transactions and starts a TRANSACTION implicitly (for example, start

Generally, the table has a Create date Field, and other databases have default options. MySQL also has the default value timestamp. However, in MySQL, the value of timestamp is updated even if it is inserted or modified! In this way, it is not the

Mysql date function. The current date in the example:Curdate () is June 24, 2013.YEAR (): displays YEARMysql> select year (curdate (); + ----------------- + | year (curdate () | + ----------------- + | 2013 | + ----------------- + 1 row in set (0.01

I. Differences in Common commands of different versions Show innodb status \ G mysql-5.1 Show engines innodb status \ G mysql-5.5 User @ '%' about grant authorization mysql-5.5 does not contain localhost Ii. Main differences between MySQL 4.1/5.0/5.

Copy codeThe Code is as follows:$ Dsn = "mysql: host = localhost; dbname = group ";$ Db = new PDO ($ dsn, 'root ','');$ Db-> exec ('set names utf8 '); $ SQL = "select conf_id from 'group' group by conf_id ";// $ Pre = $ db-> prepare ($ SQL );// $

In English, order by is the sort of rows. The default value is ascending. Order by must be followed by multiple field names.Group by is a group in English. You must have an aggregate function. At least one group flag field is required for use. What

In this example, the int char is not given their width, and the system will assign a width to it by default.M indicates the maximum display width. The maximum valid display width is 255. The display width is irrelevant to the storage size or the

I installed a mysql on the virtual machine, modified its my. cof file, and found that this configuration file is powerful, but encountered a problem: When setting character sets, set default-character-set = utf8 under [client], [mysql], and [mysqld]

Today, I will continue reading the book "mysql database development" recommended by the instructor. I encountered a problem when I saw the foreign key association problem with the innodb database, in the book, you can modify the parent table and

I have read a lot of questions about mysql. sock on the Internet before, but I didn't pay attention to the significance of this issue until I encountered the same problem in my mysql. It's confusing ......Copy codeThe Code is as follows:Zhouqian @

In MySQL, you can use select count (*) FROM table_name to query the number of records in a table. What should I do if I want to know the total number of all other records in a database? This article provides two feasible Java programs to solve this