Excuse me $lh = mysql_connect('localhost', 'root', 'root'); $qry = "SELECT * FROM aaa LIMIT 10"; $rh = mysql_unbuffered_query($qry, $lh); $thread = mysql_thread_id ( $lh ); while ( $res = mysql_fetch_row( $rh )&nb
1. Ask me about the problems encountered by mysql_unbuffered_query
Introduction: Ask about the problems encountered by mysql_unbuffered_query
##2. Does mssql in php have functions similar to the mysql_unbuffered_query function in mysql? How to solve it
Introduction: Does mssql in php have functions similar to the mysql_unbuffered_query function in mysql? Does mssql in php have functions similar to the mysql_unbuffered_query function in php? Is there such a function? What? ------Solution-------------------- mysql_unbuffered_query only takes one item at a time
3. Does mssql in php have functions similar to the mysql_unbuffered_query function of mysql? How to solve
#Introduction: Does mssql in php have functions similar to the mysql_unbuffered_query function of mysql? Does mssql in php have functions similar to the mysql_unbuffered_query function of mysql in php? Is there such a function? What is it? ------Solution--------------------mysql_unbuffered_query only takes one item at a time.
4. The difference between mysql_unbuffered_query and mysql_query
##Introduction: PHP mysql_data_seek() function definition and usage mysql_data_seek() function moves the pointer of the internal result. Syntax mysql_data_seek(data,row) Parameter Description data Required. Returns a result set of type resource. This result set is obtained from a call to mysql_query(). row required. The new result set pointer you want to set##5.
What is the purpose of using mysql_unbuffered_query during update/delete and other queries?Introduction: Mysql_unbuffered_query is used in many update/delete queries in the discuz source code. What is the purpose? According to the description in the manual (http://php.net/manual/en/function.mys...) , the main difference from mysql_query is that the query results will not be obtained and cached at once but will be updated/...
6.
mysql in PHPIntroduction: Everyone is familiar with mysql_query. Let’s briefly introduce mysql_unbuffered_query mysql_unbuffered_query (PHP 4 = 4.0.6, PHP 5) mysql_unbuffered_query -- Send a SQL query to MySQL without obtaining and caching it The row description of the result is resource mysql_unbuffered_query ( string quer
7.
Several ways for php to query the data set (mysqlIntroduction: Several ways for PHP to operate data sets 1. mysql_unbuffered_query() gives results while querying. It is not cached in the page and is suitable for big data processing. After the use is completed, the data set is automatically destroyed. Mysql_data_set($result) can no longer be used ,count) Reposition the enlightenment position of the cursor in the data set
8.
Solution to insufficient memory caused by php querying a large amount of mysql data_PHPIntroduction: This article mainly introduces the solution to insufficient memory caused by PHP querying a large amount of mysql data. The example analyzes the causes and corresponding solutions of insufficient memory during mysql query, and is more detailed. This article has analyzed the usage skills of mysql_unbuffered_query function. Friends who need it can refer to
9.
6 important practical skills in MySQL programming_MySQLIntroduction: This article summarizes 6 important practical skills in MySQL programming, including ending each line of commands with a semicolon (;); using associative arrays to access query results; TEXT, DATE, and SET data types; use mysql_unbuffered_query() to develop fast scripts; wildcards and NOT NULL
10. Solution to Insufficient Memory Caused by PHP Querying MySQL Large Data_php Tips
Introduction: This article mainly introduces PHP query The solution to insufficient memory caused by a large amount of data in mysql. The example analyzes the causes and corresponding solutions of insufficient memory during mysql query, and analyzes the usage skills of the mysql_unbuffered_query function in more detail. Friends in need can refer to the following
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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

MySQL/InnoDB supports four transaction isolation levels: ReadUncommitted, ReadCommitted, RepeatableRead and Serializable. 1.ReadUncommitted allows reading of uncommitted data, which may cause dirty reading. 2. ReadCommitted avoids dirty reading, but non-repeatable reading may occur. 3.RepeatableRead is the default level, avoiding dirty reading and non-repeatable reading, but phantom reading may occur. 4. Serializable avoids all concurrency problems but reduces concurrency. Choosing the appropriate isolation level requires balancing data consistency and performance requirements.

MySQL is suitable for web applications and content management systems and is popular for its open source, high performance and ease of use. 1) Compared with PostgreSQL, MySQL performs better in simple queries and high concurrent read operations. 2) Compared with Oracle, MySQL is more popular among small and medium-sized enterprises because of its open source and low cost. 3) Compared with Microsoft SQL Server, MySQL is more suitable for cross-platform applications. 4) Unlike MongoDB, MySQL is more suitable for structured data and transaction processing.

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.


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