SQL |查询以使用不同选项从表中选择名称

让我们考虑一下名为“ Geeks ”的下表：

G_ID	FIRSTNAME	LASTNAME	DEPARTMENT
1	Mohan	Arora	DBA
2	Nisha	Verma	Admin
3	Vishal	Gupta	DBA
4	Amita	Singh	Writer
5	Vishal	Diwan	Admin
6	Vinod	Diwan	Review
7	Sheetal	Kumar	Review
8	Geeta	Chauhan	Admin
9	Mona	Mishra	Writer

使用别名作为 NAME 从 Geeks 表中写入“FIRSTNAME”的 SQL 查询。

Select FIRSTNAME AS NAME 
from Geeks;

输出 -

NAME
Mohan
Nisha
Vishal
Amita
Vishal
Vinod
Sheetal
Geeta
Mona

SQL 查询以大写形式从 Geeks 表中写入“FIRSTNAME”。

Select upper(FIRSTNAME) 
from Geeks;

输出 -

(No column name)
MOHAN
NISHA
VISHAL
AMITA
VISHAL
VINOD
SHEETAL
GEETA
MONA

SQL 查询从 Geeks 表中查找 FIRSTNAME 的前三个字符。

Select substring(FIRSTNAME, 1, 3) 
from Geeks;

输出 -

(No column name)
Moh
Nis
Vis
Ami
Vis
Vin
She
Gee
Mon

将 Geeks 表中的 FIRSTNAME 和 LASTNAME 写入单列 COMPLETENAME 的 SQL 查询应使用空格字符分隔它们。

Select CONCAT(FIRSTNAME, ' ', LASTNAME) AS 'COMPLETENAME' 
from Geeks;

输出 -

COMPLETENAME
Mohan Arora
Nisha Verma
Vishal Gupta
Amita Singh
Vishal Diwan
Vinod Diwan
Sheetal Kumar
Geeta Chauhan
Mona Mishra

编写一个 SQL 查询以按 FIRSTNAME Ascending 打印 Geeks 表 order 中的所有 Worker 详细信息。

Select * 
from Geeks 
order by FIRSTNAME asc;

输出 -

G_ID	FIRSTNAME	LASTNAME	DEPARTMENT
4	Amita	Singh	Writer
8	Geeta	Chauan	Admin
1	Mohan	Arora	DBA
9	Mona	Mishra	Writer
2	Nisha	Verma	Admin
7	Sheetal	Kumar	Review
6	Vinod	Diwan	Review
3	Vishal	Gupta	DBA
5	Vishal	Diwan	Admin