mysql query

Indexing is the most important tool for improving query speed. Of course there are other technologies available, but generally the most significant performance difference is the correct use of the index. In the MySQL mailing list, people often ask

First, the introduction Today, there are quite a few web applications, such as Backpack,blinksale and Gmail, that integrate database technology with Ajax. This integration has a huge impact on Web applications and the user experience by providing a

This article is mainly from the principles, manuals and source analysis in PHP query MySQL return a large number of results, memory footprint problem, while the use of the MySQL C API also involved. Yesterday, a colleague in the PHP discussion

Method One: 1. Guide Table structure A way to generate a create script using MySQL. Find the script that generated the export, and modify it in MySQL syntax to create the table's column structure in the MySQL database or whatever. 2

This code is modified from Uchome code because it is handled in order to solve the efficiency of uchome. PHP implementation of MySQL read and write separation This code is modified from Uchome code because it is handled in order to solve the

Recently, a very strange MySQL problem, using different SELECT statements to query all datasets actually get different number of records. SELECT * Gets 4 records, and the Select field gets 3 records. specific questions can look at the following

Unix timestamp converted to date function: From_unixtime () Select From_unixtime (1156219870); Date converted to UNIX timestamp function: Unix_timestamp () Select unix_timestamp (' 2006-11-04 12:23:00′);

Summary: The system comes with the MySQL default character set is not GBK, so the application of the database and the development of Chinese programs bring great inconvenience, in the endless GBK and UTF8 conversion process consumes our countless

The problem with Chinese is that the code is unified or it will be garbled. 1. Database and PHP page coding Unified 2. Database Data table field and page encoding unification If you do not have the above two kinds of Chinese garbled problem, then

To make this query more efficient, add an index to one of the join columns and rerun the explain statement: mysql> ALTER TABLE t2 ADD INDEX (i2);mysql> EXPLAIN SELECT t1.i1, t2.i2 FROM t1, t2 WHERE t1.i1 = t2.i2\G*************************** 1. row *

Using the IP2ADDR function to read the IP database files directly is the most efficient, and SQL query is the most efficient one, compared with the MySQL database to store the IP data. However, the IP database file QQWry.dat is GB2312 encoded. Now I

Generally we use mysqldump to back up the MySQL database and upload it to other backup machines. If the database is large, it may be slow when the backup is transmitted, so we try to make the backup file smaller. When writing an automatic backup

Beginners | Problem "1" page cannot be passed between variables get,post,session in the latest PHP version of the automatic global variable is off, so to obtain the submitted from the previous page variable to use $_get[' foo '],$_post[' foo '],$_

I. Analysis of MySQL Query 1, first from the slow query start, slow query is the lowest cost, the most accurate measurement of query Time tool. A, start MySQL slow query, modify my.conf [Mysqld] #开启慢查询 log_slow_queries = on #指定日志文件存放位置, can be

1. The library name, the table name, the field name must use the lowercase letter, and uses the underline to divide. A) MySQL has configuration parameters lower_case_table_names, not dynamic changes, Linux system defaults to 0, that is, the library

At the end of the program, let's customize an application that synthesizes the overall framework of the PEAR buffering mechanism. we define a class called Mysql_query_cache, which buffers the query results of a SELECT. We first define the

Because group by actually does the same sort operation, group by is mostly just a grouping operation after sorting. Of course, if other aggregate functions are used when grouping, then some aggregation function calculations are also required. As a

The topic of old growth talk, in the interview will be the ability to assess, I personally think that the problem-solving ability is ranked first, higher than the learning ability priority. The ability to solve problems can not only see the

This class can build a MySQL query with an array of parameters. This class can create SELECT, INSERT, UPDATE, and DELETE statements from the specified table and field parameters. This class can create a where condition for an SQL statement, like a

1. Speaking of MySQL, we immediately think of its small size, speed, but also open source features, so it is widely used. Today we summarize the most frequent two operations in MySQL: Inserts and queries, and the optimization method. 2. Insert: 3.