Mysql Range

As the most popular open source database, MySQL is widely used in Web applications and other small and medium-sized projects. However, in many large IT companies, MySQL has gradually deviated from the original open source version after being highly optimized and customized, more like a branch, such as the Webscalesql of Facebook, which was not long ago open source. 　　Recently, Mr. Xiong has published a blog post, from the perspective of large-scale web site architecture development of the changes in MySQL application, here for you to share. This article mainly describes the different and ...

mysql tutorial to modify the table / field to add / delete table index create table test (blob_col blob, index (blob_col (10))); In mysql 5.1, myisam and innodb table prefix can reach 1000 bytes long. Note that the prefix limit should be measured in bytes, while the prefix length in the create table statement is interpreted as the number of characters. Must be considered when specifying the prefix length for columns that use multi-byte character sets. ...

First, the importance of the index The index is used to quickly find a column in a particular value of the line. Instead of using an index, MySQL must start with the first record and then read the entire table until it finds the relevant row. The larger the table, the more time it takes. If the table in the query column index, MySQL can quickly reach a location to search the middle of the data file, there is no need to see all the data. Note that if you need to access most of the rows, sequential reads are much faster since we avoid disk searches. If you use Xinhua Dictionary to find "Zhang" the Chinese characters, do not use the directory, then ...

MySQL provides standard SQL pattern matching and a format based on pattern matching of extended regular expressions like Unix utilities such as vi, grep and sed. Standard SQL Pattern Matching SQL pattern matching allows you to match any single character with "_" and "%" with any number of characters (including zero characters). In MySQL, the default SQL mode is case-insensitive. Here are some examples. Note that you can not use = or! = While you are using SQL mode, and use LIKE or NOT LIKE to compare operators ...

History of the most complete MySQL backup method, you need friends can refer to the next. I have used the backup methods are: mysqldump, mysqlhotcopy, BACKUP TABLE, SELECT INTO OUTFILE, or backup binary log (binlog), can also be directly copied data files and related configuration files. MyISAM table is saved as a file, it is relatively easy to back up, several methods mentioned above can be used. Innodb all the tables are ...

The formula for converting timestamps using execl is: Code: = (xxxxxxxxxx + 8 * 3600) / 86400 + 70 * 365 + 19 Explain the timestamp syntax using mysql tutorial statements Example: select from_unixtime (1234567890, '% y-% m -% d% h:% i:% s') Attached: In mysql, a time field storage type is int (11), how to convert into a type of character, such as store as 13270655222, ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. There are a large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred columns, consider the establishment of cluster index; Column, and each column contains duplicate values ​​can be ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. A large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred column, consider the establishment of cluster index; b. Column, ...

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 ...

PHP Tutorial MySQL Tutorial How to convert a datasheet to excel output $xlsname = "pour out information"; Header ("Content-type:application/vnd.ms-excel");  Header ("Content-disposition:filename= $xlsname. xls"); ?>.