让我们首先看一个例子并创建一个表 - mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(40),    StudentAge int,    StudentMarks int ); Query OK, 0 rows affected (0.76 sec)以下是如何知道数据库结构的查询 - mysql> show create table DemoTable;这将产生以下输出 -+---------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table         | Create Table                                                               ... 阅读更多

要排除记录，请使用 MySQL NOT IN()。让我们首先创建一个表 - mysql> create table DemoTable (    Id int ); Query OK, 0 rows affected (0.64 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values(1); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(2); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(3); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values(4); Query OK, 1 row affected (0.41 sec) mysql> insert into DemoTable values(5); Query OK, 1 row affected (0.09 sec) mysql> insert into ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable (    Name varchar(40),    Position int ); Query OK, 0 rows affected (1.17 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values('Chris', 90); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('David', 67); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('Bob', 55); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Sam', 40); Query OK, 1 row affected (0.15 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

为此，请使用聚合函数 COUNT() 和 GROUP BY 对这些特定记录进行分组以查找出现的次数。让我们首先创建一个表 - mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentSubject varchar(40) ); Query OK, 0 rows affected (5.03 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable(StudentSubject) values('MySQL'); Query OK, 1 row affected (0.78 sec) mysql> insert into DemoTable(StudentSubject) values('Java'); Query OK, 1 row affected (0.39 sec) mysql> insert into DemoTable(StudentSubject) values('MySQL'); Query OK, 1 row affected (1.12 sec) mysql> insert into DemoTable(StudentSubject) values('MongoDB'); Query OK, 1 row affected ... 阅读更多

要从记录中查找匹配项，请使用 MySQL IN()。让我们首先创建一个表 - mysql> create table DemoTable (    Id int,    FirstName varchar(20),    Gender ENUM('Male', 'Female') ); Query OK, 0 rows affected (1.73 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values(1, 'Chris', 'Male'); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable values(10, 'Emma', 'Female'); Query OK, 1 row affected (1.88 sec) mysql> insert into DemoTable values(9, 'Emma', 'Male'); Query OK, 1 row affected (0.70 sec) mysql> insert into DemoTable values(11, 'Isabella', 'Female'); Query OK, 1 row affected ... 阅读更多

为此，请使用 REGEXP。例如，字符 J、A、V 和 A。让我们首先创建一个表 - mysql> create table DemoTable (    Value varchar(50) ); Query OK, 0 rows affected (3.92 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values('XYSJGHAKLMVDFFSA'); Query OK, 1 row affected (0.67 sec) mysql> insert into DemoTable values('PQRSTJAVAL'); Query OK, 1 row affected (0.58 sec) mysql> insert into DemoTable values('SJATUVAK'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('JSTUVA'); Query OK, 1 row affected (0.32 sec)使用 select 语句显示表中的所有记录 - mysql> select ... 阅读更多

为此，您可以将 COUNT() 与 CASE 语句一起使用。让我们首先创建一个表 - mysql> create table DemoTable (    Score int ); Query OK, 0 rows affected (0.71 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values(40); Query OK, 1 row affected (0.77 sec) mysql> insert into DemoTable values(48); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(59); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(33); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(38); Query OK, 1 row affected (0.09 sec) ... 阅读更多

为此，请使用 STR_TO_DATE()。让我们首先创建一个表 - mysql> create table DemoTable (    DueDate varchar(60) ) ; Query OK, 0 rows affected (0.71 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values('12-AUG-2016'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('14-AUG-2018'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('24-AUG-2012'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('14-AUG-2012'); 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 DemoTable;这将产生以下输出 ... 阅读更多

为此，您可以将 GROUP_CONCAT() 与 GROUP BY 子句一起使用。两者都用于对重复项进行分组连接并在单行中显示。让我们首先创建一个表 - mysql> create table DemoTable (    StudentFavouriteSubject varchar(40),    StudentName varchar(40) ) ; 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('MySQL', 'Chris'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('MongoDB', 'Bob'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('MySQL', 'Sam'); Query OK, 1 row affected (0.10 sec) mysql> insert into ... 阅读更多

是的，您可以使用 MySQL 的 FIND_IN_SET() 函数搜索特定的数字。让我们首先创建一个表 -mysql> create table DemoTable (    ListOfNumbers varchar(100) ); Query OK, 0 rows affected (1.24 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values('784, 746, 894, 344'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('456, 322, 333, 456'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('654, 785, 678, 456'); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable values('123, 676, 847, 785'); Query OK, 1 row affected (0.34 ... 阅读更多