search
HomeDatabaseMysql Tutorialmysql字符串查找截取与正则表达式的联合应用

mysql字符串查找截取与正则表达式的联合应用

Jun 07, 2016 pm 03:01 PM
bmysqlstringapplicationinterceptFindregularexpression

/* 判断字符串里的内容是否是数类型 **************************************************** is_double 输入参数: str: 待分析的字符串 返回: 如果是数类型就返回1,否则返回0 */ DELIMITER $$ DROP FUNCTION IF EXISTS is_double$$ CREATE FUNCTION is_doubl

/* 判断字符串里的内容是否是数值类型 ****************************************************
    is_double
    
    输入参数:
        str:            待分析的字符串
    返回:                如果是数值类型就返回1,否则返回0
*/
DELIMITER $$
DROP FUNCTION IF EXISTS is_double$$
CREATE FUNCTION is_double(str VARCHAR(128))
RETURNS INT
BEGIN
    DECLARE iResult INT DEFAULT 0;
    
    /*NULL字符串或者空字符串*/
    IF str IS NULL OR str = ''THEN
        RETURN 0;
    END IF;

    SELECT str REGEXP '^[[:digit:]]+$|^[[:digit:]]+[\\.][[:digit:]]+$' INTO iResult;
    
    IF iResult = 1 THEN
        RETURN 1;
    ELSE
        RETURN 0;
    END IF;
END $$

DELIMITER ;



/* 分割字符串 ****************************************************
    sp_report_string_get_val
    
    功能:分割特定格式的字符串:'3.4,3.2,3.0,2.6,1.0',忽略空值或者是不合法的值
    限制:以逗号分割,分割单元以数字组成
    结果:分割之后 字符串变为'3.2,3.0,2.6,1.0'和3.4
    
    输入输出参数:
        prstring:        要分割的字符串
    输出参数:
        rval:            从字符串中取得的数值
        rcode:            返回代码:0:表示成功执行;1:表示没有取到值或者取到的不是数值
*/
DROP PROCEDURE IF EXISTS sp_get_val;
CREATE PROCEDURE sp_get_val(
                                                    INOUT    prstring    VARCHAR(128),
                                                    OUT        rval        DOUBLE,
                                                    OUT        rcode        INT UNSIGNED
                                                    )
BEGIN
    DECLARE _pos    INT UNSIGNED DEFAULT 1;        /*','的位置*/
    DECLARE _str    VARCHAR(128) DEFAULT '';    /*存放取出的字符串,之后将值赋给返回变量*/
    
    SET rval = NULL;
    SET rcode = 0;
    /*
        1)先去除空格
    */
    SET prstring = REPLACE(prstring, ' ', '');
    IF prstring = '' THEN
        SET rcode = 1;
    ELSE
        IF RIGHT(prstring, 1) != ',' THEN
            SET prstring = CONCAT(prstring, ',');
        END IF;
        
        /*
            2)找到第一个','
        */
        WHILE rval IS NULL AND prstring != '' DO
            SET _pos = LOCATE(',', prstring);
            
            IF _pos = 0 THEN
                SET rcode = 1;
            ELSE
                SET _str = SUBSTRING(prstring, 1, _pos - 1);
                
                IF is_double(_str) THEN
                    SET rval = _str;
                END IF;
                
                SET prstring = SUBSTRING(prstring, _pos + 1);
            END IF;
        END WHILE;
    END IF;
    
    IF rval IS NULL THEN
        SET rcode = 1;
    END IF;
END;



测试:

CREATE TABLE test_1(a DOUBLE);


DELIMITER $$
DROP PROCEDURE IF EXISTS sp_test_3$$
CREATE PROCEDURE sp_test_3()
BEGIN
    DECLARE _str    VARCHAR(128) DEFAULT '1,4,3.5,3.7,3.22a, , a, 34.2, 0, .1, 0., ';
    DECLARE _i        DOUBLE DEFAULT 0;
    DECLARE _j        INT UNSIGNED DEFAULT 0;
        
    WHILE _str != '' DO
        CALL sp_get_val(_str, _i, _j);
        IF _j = 0 THEN
            INSERT INTO test_1 VALUES(_i);
        END IF;
    END WHILE;
END$$
DELIMITER ;


执行:

CALL sp_test_3();

SELECT * FROM test_1;
TRUNCATE test_1;



Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Explain the ACID properties (Atomicity, Consistency, Isolation, Durability).Explain the ACID properties (Atomicity, Consistency, Isolation, Durability).Apr 16, 2025 am 12:20 AM

ACID attributes include atomicity, consistency, isolation and durability, and are the cornerstone of database design. 1. Atomicity ensures that the transaction is either completely successful or completely failed. 2. Consistency ensures that the database remains consistent before and after a transaction. 3. Isolation ensures that transactions do not interfere with each other. 4. Persistence ensures that data is permanently saved after transaction submission.

MySQL: Database Management System vs. Programming LanguageMySQL: Database Management System vs. Programming LanguageApr 16, 2025 am 12:19 AM

MySQL is not only a database management system (DBMS) but also closely related to programming languages. 1) As a DBMS, MySQL is used to store, organize and retrieve data, and optimizing indexes can improve query performance. 2) Combining SQL with programming languages, embedded in Python, using ORM tools such as SQLAlchemy can simplify operations. 3) Performance optimization includes indexing, querying, caching, library and table division and transaction management.

MySQL: Managing Data with SQL CommandsMySQL: Managing Data with SQL CommandsApr 16, 2025 am 12:19 AM

MySQL uses SQL commands to manage data. 1. Basic commands include SELECT, INSERT, UPDATE and DELETE. 2. Advanced usage involves JOIN, subquery and aggregate functions. 3. Common errors include syntax, logic and performance issues. 4. Optimization tips include using indexes, avoiding SELECT* and using LIMIT.

MySQL's Purpose: Storing and Managing Data EffectivelyMySQL's Purpose: Storing and Managing Data EffectivelyApr 16, 2025 am 12:16 AM

MySQL is an efficient relational database management system suitable for storing and managing data. Its advantages include high-performance queries, flexible transaction processing and rich data types. In practical applications, MySQL is often used in e-commerce platforms, social networks and content management systems, but attention should be paid to performance optimization, data security and scalability.

SQL and MySQL: Understanding the RelationshipSQL and MySQL: Understanding the RelationshipApr 16, 2025 am 12:14 AM

The relationship between SQL and MySQL is the relationship between standard languages ​​and specific implementations. 1.SQL is a standard language used to manage and operate relational databases, allowing data addition, deletion, modification and query. 2.MySQL is a specific database management system that uses SQL as its operating language and provides efficient data storage and management.

Explain the role of InnoDB redo logs and undo logs.Explain the role of InnoDB redo logs and undo logs.Apr 15, 2025 am 12:16 AM

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.

What are the key metrics to look for in an EXPLAIN output (type, key, rows, Extra)?What are the key metrics to look for in an EXPLAIN output (type, key, rows, Extra)?Apr 15, 2025 am 12:15 AM

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.

What is the Using temporary status in EXPLAIN and how to avoid it?What is the Using temporary status in EXPLAIN and how to avoid it?Apr 15, 2025 am 12:14 AM

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

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Best Graphic Settings
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. How to Fix Audio if You Can't Hear Anyone
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Chat Commands and How to Use Them
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use