让我们首先创建一个表 - mysql> create table DemoTable (    Value varchar(100) ); 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 DemoTable values('€986'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('§97'); 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;这将产生以下输出 -+--------+ | Value | +--------+ | €986 | | §97 +--------+ 2 rows in set (0.00 sec)以下是将不可转换字符移除为 ASCII 的查询... 阅读更多

要从两个列中选择不同的值，请使用 UNION。让我们首先创建一个表 - mysql> create table DemoTable1 (    Value1 int ); Query OK, 0 rows affected (0.56 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1 values(1); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1 values(2); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable1 values(3); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable1 values(4); 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 DemoTable1;这将... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable (    StudentId int,    StudentName varchar(100) ); Query OK, 0 rows affected (0.85 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values(NULL, 'Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(NULL, 'Robert'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(101, 'David'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(102, 'Mike'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(103, 'Sam'); Query OK, 1 row affected (0.18 sec)显示所有记录... 阅读更多

让我们首先创建一个表 - 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('190'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('230'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('120'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('189'); 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 -+-------+ | Value | +-------+ ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable (    DueDate varchar(100) ); Query OK, 0 rows affected (0.50 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values('21/10/2018'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('18/08/2019'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('01/12/2012'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('31/01/2016'); 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 -+------------+ | DueDate ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable1 (    PersonId int,    Value 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 DemoTable1 values(100, 78); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable1 values(101, 67); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1 values(102, 89); 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 DemoTable1;这将产生以下输出 -+----------+-------+ | PersonId | Value | +----------+-------+ |      100 ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable (    FirstName varchar(100),    CountryName varchar(100) ); Query OK, 0 rows affected (0.56 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable values('Adam', 'US'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('David', 'AUS'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Chris', 'UK'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('John', 'US'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Carol', 'AUS'); Query OK, 1 row affected (0.14 sec)显示所有记录... 阅读更多

以下是使用 CREATE TABLE IF NOT EXISTS 检查表是否已存在的语法 -create table if not exists yourTableName (    yourColumnName1 dataType,    .    .    .    .    N ); insert into yourTableName values(yourValue1, .......N);让我们首先创建一个表 - mysql> create table if not exists DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentSubject 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(StudentSubject) values('Java'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable(StudentSubject) values('MySQL'); ... 阅读更多

为此，您可以使用 FIND_IN_SET()。 让我们先创建一个表 -mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Value varchar(100) ); Query OK, 0 rows affected (2.49 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable(Value) values('100;200;300'); Query OK, 1 row affected (0.42 sec) mysql> insert into DemoTable(Value) values('1;300;400'); Query OK, 1 row affected (0.58 sec) mysql> insert into DemoTable(Value) values('6;7;8;9;10'); Query OK, 1 row affected (0.29 sec) mysql> insert into DemoTable(Value) values('1;2;3;4;5'); Query OK, 1 row affected (9.36 sec) mysql> insert into DemoTable(Value) values('3;8;9;10'); Query OK, 1 ... 阅读更多

让我们先创建一个表 &mnus;mysql> create table DemoTable (    `timestamp` timestamp ); Query OK, 0 rows affected (1.12 sec)使用 insert 命令在表中插入一些记录 -mysql> insert into DemoTable values(now()); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values('00:00:00'); Query OK, 1 row affected (0.73 sec) mysql> insert into DemoTable values('2018-01-10 12:34:45'); Query OK, 1 row affected (0.80 sec) mysql> insert into DemoTable values('2019-12-31 10:50:45'); Query OK, 1 row affected (0.84 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 -+---------------------+ | timestamp ... 阅读更多