让我们首先创建一个表 - mysql> create table DemoTable719 (FirstNumber int, SecondNumber int); Query OK, 0 rows affected (0.57 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable719 values(20, 10); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable719 values(500, 50); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable719 values(400, 20); Query OK, 1 row affected (0.11 sec)使用 select 语句显示表中的所有记录 - mysql> select *from DemoTable719;这将产生以下输出 - +-------------+--------------+ | FirstNumber | SecondNumber | +-------------+--------------+ | 20          | ... 阅读更多

为此，您可以使用子查询。让我们首先创建一个表 - mysql> create table DemoTable618 (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentFirstName varchar(100) ); Query OK, 0 rows affected (1.45 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable618(StudentFirstName) values('David'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable618(StudentFirstName) values('Chris'); Query OK, 1 row affected (0.44 sec) mysql> insert into DemoTable618(StudentFirstName) values('Robert'); Query OK, 1 row affected (0.54 sec) mysql> insert into DemoTable618(StudentFirstName) values('Sam'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable618(StudentFirstName) values('Mike'); Query OK, 1 ... 阅读更多

要跳过行，您可以使用 OFFSET。让我们首先创建一个表 - mysql> create table DemoTable617(Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100)); Query OK, 0 rows affected (1.70 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable617(FirstName) values('John'); Query OK, 1 row affected (0.39 sec) mysql> insert into DemoTable617(FirstName) values('Sam'); Query OK, 1 row affected (0.39 sec) mysql> insert into DemoTable617(FirstName) values('Carol'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable617(FirstName) values('Mike'); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable617(FirstName) values('David'); Query OK, 1 row affected (0.17 sec) ... 阅读更多

为此，您可以使用聚合函数 SUM()。让我们首先创建一个表：mysql> create table DemoTable616 (Price varchar(100)); Query OK, 0 rows affected (0.59 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable616 values('€200.00'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable616 values('€300.00'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable616 values('€500.00'); Query OK, 1 row affected (0.12 sec)使用 select 语句显示表中的所有记录 - mysql> select *from DemoTable616;这将产生以下输出 - +-----------+ | Price     | +-----------+ | €200.00 | | ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable615 (EmployeeId varchar(100), EmployeeName varchar(100)); Query OK, 0 rows affected (0.62 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable615 values('EMP-101', 'Adam'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable615 values('EMP-1001', 'David'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable615 values('EMP-1002', 'Chris'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable615 values('EMP-1003', 'Robert'); Query OK, 1 row affected (0.21 sec)使用 select 语句显示表中的所有记录 - mysql> select *from DemoTable615;这将产生以下输出 - +------------+--------------+ | ... 阅读更多

为此，使用 LTRIM() 和 RTRIM()，因为名称相似但具有不同的左右空格分配。例如，“ John “ 和 “John”。让我们首先创建一个表 - mysql> create table DemoTable614 (EnterName varchar(100), ReennterName varchar(100)); Query OK, 0 rows affected (0.97 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable614 values(' John ', 'John'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable614 values('Carol ', 'Bob'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable614 values('David ', 'David'); Query OK, 1 row affected (0.23 sec)显示所有记录 ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable613 (Id int, Age int, isMarried tinyint(1)); Query OK, 0 rows affected (0.54 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable613 values(100, 29, 0); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable613 values(200, 22, 0); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable613 values(300, 30, 1); Query OK, 1 row affected (0.19 sec)使用 select 语句显示表中的所有记录 - mysql> select *from DemoTable613;这将产生以下输出 - +------+------+-----------+ | Id   | Age  | isMarried | +------+------+-----------+ ... 阅读更多

对于条件，使用 IF()。以下是语法 - IF(yourCondition, trueStatement, falseStatement);让我们首先创建一个表 - mysql> create table DemoTable612 (Number1 int, Number2 int, Score int); Query OK, 0 rows affected (0.47 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable612 values(10, 20, 1000); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable612 values(30, 40, 500); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable612 values(50, 70, 1200); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable612 values(100, 120, 400); Query OK, 1 row affected (0.16 sec)显示所有记录 ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable611 (DOB date); Query OK, 0 rows affected (0.99 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable611 values('1996-04-21'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable611 values('2001-01-31'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable611 values('2004-12-21'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable611 values('2000-02-03'); Query OK, 1 row affected (0.14 sec)显示表中的所有记录使用 select 语句 - mysql> select *from DemoTable611;这将产生以下输出 - +------------+ | DOB       | ... 阅读更多

首先，我们创建一个表：
mysql> create table DemoTable610 (SubjectName varchar(100));
Query OK, 0 rows affected (0.63 sec)
使用insert命令在表中插入一些记录：
mysql> insert into DemoTable610 values('MySQL');
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable610 values('Java');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable610 values('MySQL');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable610 values('MongoDB');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable610 values('MySQL');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable610 values('MySQL');
Query OK, 1 row affected (0.08 sec)
mysql> ... 阅读更多