为此，使用带有 ORDER BY 的 CASE 语句。让我们首先创建一个表 - mysql> create table DemoTable1937    (    Name varchar(20)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1937 values('Chris'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1937 values(NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1937 values('Adam'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1937 values('John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1937 values(''); Query OK, 1 row affected (0.00 sec) ... 阅读更多

要执行多个插入操作，语法如下 - insert into yourTableName(yourColumnName1, yourColumnName2, yourColumnName3, ..N)    select yourValue1 as yourColumnName1, yourValue2 as yourColumnName2, yourValue3 as yourColumnName3, ......N    union    select yourValue1 as yourColumnName1, yourValue2 as yourColumnName2, yourValue3 as yourColumnName3, ......N . . N要理解上述语法，让我们创建一个表 - mysql> create table DemoTable1936    (    StudentId int,    StudentName varchar(20),    StudentCountryName varchar(20)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1936(StudentId, StudentName, StudentCountryName)    select 1001 as StudentId, 'Chris' as StudentName, 'US' ... 阅读更多

为此，使用 RLIKE 并按以下语法过滤记录 &Minus;select * from yourTableName    where yourColumnName rlike 'yourValue1|yourValue2';让我们首先创建一个表 - mysql> create table DemoTable1935    (    Subject varchar(20)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1935 values('MySQL'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1935 values('Python'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1935 values('MongoDB'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1935 values('SQL Server'); Query OK, 1 row affected (0.00 ... 阅读更多

要获取平均值，请使用 AVG() 并将其与 DISTINCT 一起使用以从不同的记录中计算。让我们首先创建一个表 - mysql> create table DemoTable1934    (    StudentName varchar(20),    StudentMarks int    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1934 values('Chris', 56); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1934 values('Chris', 56); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1934 values('David', 78); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1934 values('David', 78); Query OK, 1 row affected ... 阅读更多

让我们首先创建一个表 - mysql> create table DemoTable1933    (    ClientName varchar(20)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1933 values('Chris Brown'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1933 values('David Miller'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1933 values('Adam Smith'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1933 values('John Doe'); Query OK, 1 row affected (0.00 sec)使用 select 语句显示表中的所有记录 - mysql> select * from DemoTable1933;这将产生 ... 阅读更多

使用 ORDER BY 来修复记录，然后显示 select * from yourTableName order by yourColumnName1=yourValue desc, yourColumnName2;让我们首先创建一个表 - mysql> create table DemoTable1932    (    UserName varchar(20),    ShippingDate date    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1932 values('Chris', '2018-10-12'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1932 values('David', '2019-04-11'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1932 values('Mike', '2016-12-04'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1932 values('Carol', '2017-12-26'); Query OK, 1 ... 阅读更多

对于特定格式的月份和年份，请使用 DATE_FORMAT() 以及 STR_TO_DATE()。让我们首先创建一个表 - mysql> create table DemoTable1931    (    ShippingDate varchar(40)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1931 values('10-11-2017'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1931 values('31-01-2019'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1931 values('02-02-2018'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1931 values('10-06-2013'); Query OK, 1 row affected (0.00 sec)使用 select 显示表中的所有记录 ... 阅读更多

为此，您可以使用 date_add()。让我们首先创建一个表 - mysql> create table DemoTable1930    (    DueTime datetime    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1930 values('2017-10-21'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1930 values('2019-12-14'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1930 values('2018-11-26'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1930 values('2014-06-16'); Query OK, 1 row affected (0.00 sec)使用 select 语句显示表中的所有记录 - mysql> select * from DemoTable1930;这将 ... 阅读更多

要重置主键，首先使用 TRUNCATE 表，然后使用 ALTER TABLE。让我们首先创建一个表 - mysql> create table DemoTable1929    (    UserId int NOT NULL AUTO_INCREMENT,    PRIMARY KEY(UserId)    ); Query OK, 0 rows affected (0.00 sec)使用 insert 命令在表中插入一些记录 - mysql> insert into DemoTable1929 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1929 values(); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1929 values(); Query OK, 1 row affected (0.00 sec)使用 select 语句显示表中的所有记录 - mysql> select * from DemoTable1929;这将 ... 阅读更多

要在存储过程中向表中插入数据，语法如下 - create procedure yourProcedureName(OptionalParameter)    begin    insert into yourTableName() values(yourValue1, yourValue2, ...N); end要理解上述语法，让我们首先创建一个表 - mysql> create table DemoTable1928    (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Name varchar(20),    Age int    ); Query OK, 0 rows affected (0.00 sec)以下是创建存储过程的查询 - mysql> delimiter // mysql> create procedure insert_demo(IN Name varchar(40), IN Age int)    begin    insert into DemoTable1928(Name, Age) values(Name, Age);    end    // Query OK, ... 阅读更多