找到关于 MySQLi 的4219 篇文章
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
610 次浏览
要获取以特定字符开头的名称,需要使用 LIKE。让我们首先创建一个表:mysql> create table DemoTable ( StudentFirstName varchar(20) ); Query OK, 0 rows affected (1.01 sec)以下是使用 insert 命令在表中插入一些记录的查询:mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Carol'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Johnny'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('Chris'); ... 阅读更多
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
168 次浏览
要在 MySQL 查询中使用 BirthDate 列获取年龄,可以使用 datediff()。让我们首先创建一个表:mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, DateOfBirth date ); Query OK, 0 rows affected (1.46 sec)以下是使用 insert 命令在表中插入一些记录的查询:mysql> insert into DemoTable(DateOfBirth) values('2010-01-21'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(DateOfBirth) values('1993-04-02'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(DateOfBirth) values('1999-12-01'); Query OK, 1 row affected (1.53 sec) mysql> insert into DemoTable(DateOfBirth) values('1998-11-16'); Query OK, 1 row ... 阅读更多
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
663 次浏览
为了在 MySQL 表中选择特定范围的值,可以使用 WHERE 子句。让我们首先创建一个表:mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerName varchar(200), CustomerAge int, isRegularCustomer bool ); Query OK, 0 rows affected (0.57 sec)以下是使用 insert 命令在表中插入一些记录的查询:mysql> insert into DemoTable(CustomerName, CustomerAge, isRegularCustomer)values('Chris', 24, true); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(CustomerName, CustomerAge, isRegularCustomer)values('Robert', 26, false); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable(CustomerName, CustomerAge, isRegularCustomer)values('Mike', ... 阅读更多
![karthikeya Boyini](https://tutorialspoint.com/assets/profiles/13518/profile/60_31598-1537784993.jpg)
82 次浏览
使用 DATE_FORMAT() 并设置说明符以仅显示月份名称和年份。让我们首先创建一个表 - mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, AdmissionDate date ); Query OK, 0 rows affected (0.69 sec)使用 insert 命令在表中插入记录 - mysql> insert into DemoTable(AdmissionDate) values('2013-04-21'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(AdmissionDate) values('2014-01-31'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(AdmissionDate) values('2016-09-01'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(AdmissionDate) values('2018-12-12'); Query OK, 1 row affected (0.11 sec) mysql> insert ... 阅读更多
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
1K+ 次浏览
要选择逗号分隔列表的第一个元素,可以使用 SUBSTRING_INDEX()。让我们首先创建一个表:mysql> create table DemoTable ( CSV_Value varchar(200) ); Query OK, 0 rows affected (0.81 sec)以下是使用 insert 命令在表中插入一些记录的查询。我们以逗号分隔的整数列表的形式插入了记录:mysql> insert into DemoTable values('10, 20, 50, 80'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('100, 21, 51, 43'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('1, 56, 103, 1090'); Query OK, 1 row affected (0.26 ... 阅读更多
![Samual Sam](https://tutorialspoint.com/assets/profiles/13514/profile/60_83486-1512649303.jpg)
506 次浏览
要了解 MySQL 表数据的存放位置,可以使用以下语法 - select @@datadir;也可以为此使用 SHOW VARIABLES 命令。以下是语法 - show variables where Variable_name ='datadir';让我们实现上述语法来了解 MySQL 表在哪里存储数据 - mysql> select @@datadir;这将产生以下输出 - +---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ ... 阅读更多
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
126 次浏览
要在一个查询中获取最大值和最小值,请使用聚合函数 min() 和 max()。让我们首先创建一个表:mysql> create table DemoTable ( FirstValue int, SecondValue int ); Query OK, 0 rows affected (0.66 sec)以下是使用 insert 命令在表中插入一些记录的查询:mysql> insert into DemoTable values(10, 30); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(30, 60); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(100, 500); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(50, 80); Query OK, ... 阅读更多
![karthikeya Boyini](https://tutorialspoint.com/assets/profiles/13518/profile/60_31598-1537784993.jpg)
273 次浏览
要查找以数字开头的字符串,请使用正则表达式。让我们首先创建一个表 - mysql> create table DemoTable ( Id varchar(200) ); Query OK, 0 rows affected (0.59 sec)使用 insert 命令在表中插入记录 - mysql> insert into DemoTable values('123User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('_$123User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('User123456'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('0000User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('&^*User'); Query OK, 1 row affected (0.24 sec)显示记录 ... 阅读更多
![Krantik Chavan](https://tutorialspoint.com/assets/profiles/13545/profile/60_126883-1512724834.jpg)
527 次浏览
要获取列中仅出现一次的值的数量,可以使用 GROUP BY HAVING。让我们首先创建一个表:mysql> create table DemoTable ( Name varchar(20) ); Query OK, 0 rows affected (0.55 sec)以下是使用 insert 命令在表中插入一些记录的查询:mysql> insert into DemoTable values('Larry'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Larry'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('Sam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into ... 阅读更多
![Samual Sam](https://tutorialspoint.com/assets/profiles/13514/profile/60_83486-1512649303.jpg)
820 次浏览
要导出 MySQL 中的特定列数据,请使用 OUTFILE - select yourColumnName from yourTableName into outfile 'yourLocationOfFile';让我们首先创建一个表 - mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentFirstName varchar(20), StudentLastName varchar(20) ); Query OK, 0 rows affected (0.54 sec)使用 insert 命令在表中插入记录 - mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Doe'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('David', 'Miller'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Smith'); Query OK, 1 row affected (0.15 sec) mysql> insert into ... 阅读更多