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PHP-MySQL基本操作(转载)

   日期:2022-02-11

// 1.防止页面中文乱码

header("content-type:text/html;charset=utf-8");
 

// 链接数据库

@$conn = new mysqli('localhost', 'root', '');

echo $conn == true ? '数据库连接成功' : '数据库连接失败';
 

// 2.连接到MySQL后设置字符集(防止存入中文乱码)

mysqli_set_charset($conn, 'utf8');
 

// 创建数据库

$createDatabaseSql = "create database ProsperLee01 charset utf8";

// 删除数据库

$dropDatabaseSql = "drop database ProsperLee01";

// 查询数据库

$showDatabaseSql = "show databases";

// 查询创建的数据库信息

$showCreateDatabaseSql = "show create database ProsperLee01";

// 修改数据库(不能修改数据库的名字,只能修改字符集和校对集)语法:alter database 数据库 character set=新的字符集 collate=新的校对集

$alterDatabaseSql1 = "alter database ProsperLee01 character set=gbk collate=gbk_Chinese_ci";

$alterDatabaseSql2 = "alter database ProsperLee01 charset=utf8 collate=utf8_general_ci";

// 查询字符集

$showCharsetSql = "show charset";

// 查询校对集

$showCollationSql = "show collation";

// 使用数据库

$useDatabaseSql = "use ProsperLee01";

// 创建数据表 语法 CREATE TABLE 库名 表名 (字段名 字段类型 字段选项, 字段名 字段类型 字段选项···) 表选项; (表选项:表字符集(charset=utf8)和数据引擎(engine=引擎))

$createTableSql =<<
    CREATE TABLE `prosperlee01`.`Lee01` (

        `name` varchar(20) DEFAULT '小明同学' NOT NULL COMMENT '姓名',

        `sex` varchar(5) NULL COMMENT '性别',

        `age` int(2) NULL COMMENT '年龄',

        `index` int NOT NULL AUTO_INCREMENT COMMENT '序号',

        `id` varchar(8) NOT NULL COMMENT 'id',

        PRIMARY KEY (`index`, `id`)

    ) ENGINE=InnoDB DEFAULT CHARSET=utf8

sss;

// 查询数据表

$showTablesSql = "show tables";

// 查看数据表结构

$descTableSql = "desc lee01";

// 查询创建的数据表

$showCreateTableSql = "show create table Lee01";

// 修改表名 alter table 旧表名 rename [to] 新表名

$alterTableNameSql = "alter table lee01 rename to newlee01";

// 添加新字段

$alterTableAddFieldSql = "alter table lee01 add realname varchar(50) not null default '用户名' comment '真实姓名'";

// 删除字段 alter table 表名 drop column 字段名

$alterTableDropFieldSql = "alter table lee01 drop column phone";

// 修改表的字段类型   ALTER TABLE 表名 MODIFY COLUMN 字段名 字段类型定义;

$alterTableModifyFieldSql = "ALTER TABLE lee01 MODIFY COLUMN id VARCHAR(32)";

// 修改表的字段名(修改后原始字段存的值不会变,新存入的值不填写变成默认值) alter table 表名 change 原字段名  新字段名  字段的类型

$alterTableChangeFieldSql = "ALTER TABLE lee01 change realname phone VARCHAR(11) default '01234567890' comment '电话号'";

// 插入数据 INSERT INTO table_name (列1, 列2,...) VALUES (值1, 值2,....)

$insertIntoDataSql1 = "INSERT INTO Lee01 (`sex`,`age`,`id`) VALUES ('女',20,'88888888')";

$insertIntoDataSql2 = "INSERT INTO Lee01 (`name`,`sex`,`age`,`id`) VALUES ('Lee','女',20,'66666666')";

$insertIntoDataSql = <<
    INSERT INTO Lee01 ( `name`, `sex`, `age`, `id` )

    VALUES

        ( '张三', '女', 16, '12345678' ),

        ( '李四', '男', 18, '87654321' ),

        ( '王五', '女', 20, '22222222' ),

        ( '赵六', '女', 21, '11111111' ),

        ( '八爷', '男', 26, '14725836' ),

        ( '九少', '男', 16, '66666666' )

sss;

// 查询语句

$selectDataSql1 = "select * from lee01";

$selectDataSql2 = "select * from lee01 where sex = '女' and age = '20'";

$selectDataSql3 = "select * from lee01 where age = '20' or age = '16'";

$selectDataSql4 = "select * from lee01 where not age = '20'";

$selectDataSql5 = "select name,age from lee01 where age = '20' or age = '16'";

// in 查询指定index (无则跳过)

$selectDataSql6 = "select name,age from lee01 where `index` in (1,2,4,6)";

// between 语法:select 查询字段 from 表名 where 字段 between 最小值 and 最大值;

$selectDataSql7 = "select name from lee01 where `index` between 2 and 5";

// 查询数据量(启用别名)

$selectDataSql8 = "select count(`index`) as count from lee01";

// like 模糊查询(注:直接写字符,严格匹配)%匹配任何字符

$selectDataSql9 = "select * from lee01 where name like '%三%'";

// group by (只能查看分组后的数量,而不能查看分组后的信息)

$selectDataSql10 = "select count(sex),sex from lee01 group by sex";

// 查询性别数量大于2个的性别的数量

$selectDataSql11 = "select count(sex) as sexnum,sex from lee01 group by sex having sexnum>2";

// 查询正序(asc)倒序(desc)

$selectDataSql12 = "select * from lee01 order by id asc";

// 分页查询 (limit 下标,查询数量)

$selectDataSql13 = "select * from lee01 order by `index` asc limit 0,2";

$selectDataSql14 = "select * from lee01 order by `index` asc limit 2,2";

$selectDataSql15 = "select * from lee01 order by `index` asc limit 4,2";

// 删除数据表

$dropTableSql = "drop table lee01";

// 清空数据表(同时删除自增字段的定义)

$truncateTableSql1 = "truncate table lee01";

// 清空数据表(删除表中的所有行,一行一行的删)(delete 保留原有自增字段,再次创建不占用删除字段)

$deleteTableSql1 = "delete from lee01";

// 按条件删除 delete from 表名 [where条件] [order排序] [limit限定](删除范围数据可能会用到order、limit)

$deleteTableSql2 = "delete from lee01 where phone = '用户名'";

// 修改数据(无条件全改)

$updateSetSql = "update lee01 set name = 'ProsperLee',age=23 where id = '87654321'";


// 使用数据库

mysqli_select_db($conn, 'ProsperLee01'); // 使用数据库
 

// 3.设置通信编码

mysqli_query($conn, "set names utf8");

 
// 执行sql语句

$result = mysqli_query($conn, $selectDataSql1);

var_dump($result);
 

/**

 * fetch_assoc() 每次拿1条数据

 * fetch_all() 拿出全部数据

 */

$showData = $result->fetch_all();

var_dump($showData);

 
// 关闭数据库

mysqli_close($conn);