让我们先创建一个表 -mysql> create table DemoTable (    AdmissionDate date ); Query OK, 0 rows affected (0.87 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('2019-08-24'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('2019-08-25'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('2019-08-20'); Query OK, 1 row affected (0.24 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable;这将产生以下输出 -+---------------+ | AdmissionDate | +---------------+ | 2019-08-24 | | 2019-08-25 | ... 阅读更多

以下是语法 -select *from yourTableName order by yourColumnName*1, yourColumnName;让我们先创建一个表 -mysql> create table DemoTable (    Value 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 DemoTable values('90'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('86'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable values('45'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('85'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable values('085'); Query OK, 1 row affected (0.14 sec) ... 阅读更多

以下是语法 -select if(yourColumnName, 1, -1) from yourTableName;让我们先创建一个表 -mysql> create table DemoTable (    isMarried boolean ); Query OK, 0 rows affected (0.60 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(false); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(true); Query OK, 1 row affected (0.36 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable;这将 ... 阅读更多

让我们先创建一个表 -mysql> create table DemoTable (    Value varchar(100) ); Query OK, 0 rows affected (0.75 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('100'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(''); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values('200'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable values(null); 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 DemoTable;这将产生以下输出 -+-------+ | Value | +-------+ ... 阅读更多

使用 BETWEEN 查找两个日期之间的登录次数。让我们先创建一个表 -mysql> create table DemoTable (    Login datetime ); Query OK, 0 rows affected (0.66 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('2019-08-10'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('2019-08-12'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('2019-08-20'); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values('2019-08-24'); 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 DemoTable;这将 ... 阅读更多

让我们先创建一个表 -mysql> create table DemoTable1045 (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    FirstName varchar(100) )AUTO_INCREMENT=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 DemoTable1045(FirstName) values('John'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1045(FirstName) values('Chris'); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable1045(FirstName) values('Robert'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable1045(FirstName) values('Mike'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1045(FirstName) values('Adam'); Query OK, 1 row affected (0.08 sec)显示所有记录 ... 阅读更多

为此，使用 ORDER BY LIKE 运算符。让我们先创建一个表 -mysql> create table DemoTable (    Name varchar(100) ); Query OK, 0 rows affected (0.60 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Adam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Jace'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected (0.09 sec) mysql> insert into ... 阅读更多

为此，将 MAX() 与子查询一起使用。这里，MAX() 用于获取最大金额。让我们先创建一个表 -mysql> create table DemoTable (    ProductId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    ProductName varchar(100),    ProductAmount int ); Query OK, 0 rows affected (0.53 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable(ProductName, ProductAmount) values('Product-1', 60); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(ProductName, ProductAmount) values('Product-2', 40); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(ProductName, ProductAmount) values('Product-3', 75); Query OK, 1 row affected (0.15 sec) mysql> ... 阅读更多

要比较第一个日期和最后一个日期，请将 TIME_TO_SEC() 与 MAX() 和 MIN() 一起使用。让我们先创建一个表 -mysql> create table DemoTable (    UserName varchar(100),    UserPostDatetime datetime ); Query OK, 0 rows affected (0.65 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('Adam', '2019-08-24 11:10:00'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Adam', '2019-08-24 11:20:00'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Adam', '2019-08-24 11:50:00'); Query OK, 1 row affected (0.13 sec)使用 select 语句显示表中的所有记录 -mysql> ... 阅读更多

首先让我们创建一个表 -mysql> create table DemoTable (    Id int,    Name varchar(100) ); Query OK, 0 rows affected (0.60 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values(100, 'Chris'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(110, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(120, 'Robert'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(130, 'Mike'); Query OK, 1 row affected (0.13 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable;这将产生... 阅读更多