Sql唯一选择

代码示例

DISTINCT SQL

SELECT DISTINCT column1, column1, ..... FROM TABLE
/*DISTINCT WILL NOT SELECT THE SAME VALUES IN SAME COLUMN*/

sql插入对于每个不同的价值

insert into your_table (col1, col2, col3)
select distinct col1, 'newval', col3
from your_table

每个不同值的sql插入

insert into your_table (col1, col2, col3)
select distinct col1, 'newval', col3
from your_table

sql唯一

This constraint ensures all values in a column are unique.
Example 1 (MySQL): Adds a unique constraint to the id column when
creating a new users table.
CREATE TABLE IF NOT EXISTS users (
id int NOT NULL,
name varchar(255) NOT NULL,
UNIQUE (id)
);
Example 2 (MySQL): Alters an existing column to add a UNIQUE
constraint.
ALTER TABLE users
ADD UNIQUE (id);

sql独特

This constraint ensures all values in a column are unique.
Example 1 (MySQL): Adds a unique constraint to the id column when
creating a new users table.
CREATE TABLE IF NOT EXISTS users (
id int NOT NULL,
name varchar(255) NOT NULL,
UNIQUE (id)
);
Example 2 (MySQL): Alters an existing column to add a UNIQUE
constraint.
ALTER TABLE users
ADD UNIQUE (id);

如何在sql中选择唯一元素

DISTINCT
- select distinct * from employees; ==> 
  retrieves any row if it has at
  least a single unique column.

- select distinct first_name from employees; ==> 
      retrieves unique names
     from table. (removes duplicates)
     
- select distinct count(*) from employees;
     retrieve number of unique rows
     if any row has at least a single unique data.

sql中的唯一元素

DISTINCT
- select distinct * from employees; ==> retrieves any row if it has at
least a single unique column.
- select distinct first_name from employees; ==> retrieves unique names
from table. (removes duplicates)
- select distinct count(*) from employees; retrieve number of unique rows
if any row has at least a single unique data.

sql唯一的选择

SELECT DISTINCT col1, col2, ....
FROM table_name;

SELECT col1, MIN(col2)
FROM table_name
GROUP BY col1;

类似页面

带有示例的类似页面

其他语言

此页面有其他语言版本

empty row

Русский

..................................................................................................................

Ссылка

English

..................................................................................................................

Link

Italiano

..................................................................................................................

Link

Polski

..................................................................................................................

Link

Română

..................................................................................................................

Legătură

한국어

..................................................................................................................

링크

हिन्दी

..................................................................................................................

लिंक

Français

..................................................................................................................

Lien

Türk

..................................................................................................................

Atıf

Česk

..................................................................................................................

Odka

Português

..................................................................................................................

Referênci

ไทย

..................................................................................................................

เชื่อมโยง

Español

..................................................................................................................

Referencia

Slovenský

..................................................................................................................

Odkaz

Балгарскі

..................................................................................................................

Спасылка

Íslensk

..................................................................................................................

Link

受欢迎的此类别

标籤的相关热门网页

empty row

sql select distinct on

sql select from column like with different value

如何从sql中的列中获取唯一值

获取唯一的列值

在mysql中选择一个唯一的列