要列出 MySQL 中的临时表列，我们首先创建一个临时表。以下是一个示例。我们创建了一个包含学生详细信息的一些列的临时表 -mysql> CREATE TEMPORARY TABLE DemoTable745 (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(100),    StudentAge int,    StudentAddress varchar(100),    StudentCountryName varchar(20) ); Query OK, 0 rows affected (0.00 sec)以下是在 MySQL 中列出临时表列的查询 -mysql> show columns from DemoTable745;这将产生以下输出 -+--------------------+--------------+------+-----+---------+----------------+ | Field              | Type         ... 阅读更多

是的，除了第一位数字外，我们可以将列值的所有数字替换为零。让我们首先查看一个示例并创建一个表 -mysql> create table DemoTable744 (Number varchar(100)); 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 DemoTable744 values('537737736252'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable744 values('989000099999'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable744 values('343225666666664533'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable744 values('4322111899494'); Query OK, 1 row affected (0.15 sec)显示表中的所有记录 ... 阅读更多

要仅保留前两个字符并删除其余字符，请使用 SUBSTRING()。让我们首先创建一个表 -mysql> create table DemoTable743 (SubjectName varchar(100)); 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 DemoTable743 values('MySQL'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable743 values('Java'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable743 values('MongoDB'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable743 values('Python'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable743 values('Data Structure'); Query OK, 1 row affected (0.68 ... 阅读更多

为此，请使用 REGEXP。让我们首先创建一个表 -mysql> create table DemoTable(SubjectCode varchar(100)); Query OK, 0 rows affected (0.89 sec)使用 insert 命令在表中插入一些记录。记录包含文本、数字和特殊字符 -mysql> insert into DemoTable values('Java899@22'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('C#'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('~Python232'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('MongoDB%'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('C123456'); Query OK, 1 row affected (0.37 sec)显示所有 ... 阅读更多

让我们首先创建一个表 -mysql> create table DemoTable742 (Value varchar(100)); Query OK, 0 rows affected (2.91 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable742 values('632535MIT'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable742 values('US%UK'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable742 values('56%78'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable742 values('%_1234'); Query OK, 1 row affected (0.09 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable742;这将产生以下输出 -+-----------+ | Value | ... 阅读更多

让我们首先创建一个表 -mysql> create table DemoTable741 (Number int); Query OK, 0 rows affected (0.61 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable741 values(70); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable741 values(55); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable741 values(89); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable741 values(79); Query OK, 1 row affected (0.35 sec) mysql> insert into DemoTable741 values(34); Query OK, 1 row affected (0.17 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable741;这将 ... 阅读更多

使用 LIKE 查找包含双引号的记录。以下是语法 -select *from yourTableName where yourColumnName LIKE '%"%';让我们首先创建一个表 -mysql> create table DemoTable740 (Value varchar(100)); Query OK, 0 rows affected (0.49 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable740 values("\""); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable740 values("\"John"); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable740 values("Sam"); 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 DemoTable740;这将产生以下输出 -+-------+ | ... 阅读更多

让我们首先创建一个表 -mysql> create table DemoTable739 (Price int); 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 DemoTable739 values(100); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable739 values(50); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable739 values(1200); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable739 values(500); Query OK, 1 row affected (0.37 sec) mysql> insert into DemoTable739 values(800); Query OK, 1 row affected (0.20 sec)使用 select 语句显示表中的所有记录 -mysql> select *from DemoTable739;这将 ... 阅读更多

假设表中有一些列，一列用于图像路径，另一列用于点赞数。但是，第一列是自动增量的 Id，如下所示 -mysql> create table DemoTable(    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, ImagePath varchar(100), UpvoteValue int ); Query OK, 0 rows affected (0.72 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable(ImagePath, UpvoteValue) values('Image1.jpeg', 90); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable(ImagePath, UpvoteValue) values('Image2.jpeg', 10); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable(ImagePath, UpvoteValue) values('Image3.jpeg', 120); Query OK, 1 ... 阅读更多

要查找包含 a-z、A-Z 和 0-9 的字符串，请使用 BINARY REGEXP 以及 AND 运算符。让我们首先创建一个表 -mysql> create table DemoTable738 (UserId varchar(100)); Query OK, 0 rows affected (0.81 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable738 values('John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable738 values('sAm456'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable738 values('98Carol'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable738 values('67david'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable738 values('69MIKE'); Query OK, 1 row affected (0.18 ... 阅读更多