————-SQL Function————-
—判断数据库是否存在
if exists (select * from sys.databases where name = ‘数据库名’)
drop database [数据库名]
–判断表是否存在
if exists (select * from sysobjects where id = object_id(N'[表名]’) and OBJECTPROPERTY(id, N’IsUserTable’) = 1)
drop table [表名]
–判断存储过程是否存在
if exists (select * from sysobjects where id = object_id(N'[pro]’) and OBJECTPROPERTY(id, N’IsProcedure’) = 1)
print ‘exists’
else
print ‘not exists’
–判断函数是否存在
IF OBJECT_ID (N’函数名’) IS NOT NULL
DROP FUNCTION dnt_split
–left(),right(),charindex()—-
begin
declare @str varchar(20)
set @str=’hello every body’;
print left(@str,7) –print result->hello e
print right(@str,7) –print result->ry body
print charindex(‘ ‘,@str) –print result->6
end
— cast()数据类型转换函数———
begin
select CAST(‘123’ as int)
select CAST(123.0 as varchar(6))
select CAST(‘12.5’ as decimal(5,0)) –四舍五入
select CAST(’12’ as float)
end
— 将查询出来的多列组成为一列的字符串—-
begin
select ‘学生编号：’+scStuNo+’成绩:’+cast(scScore as varchar(6)) as 学生成绩 from score_tb
end
–SQL While循环 计算1加到100的和—–
begin
declare @sum int,@num int
set @num=1
set @sum=0
while @num<101
begin
set @sum=@sum+@num
set @num=@num+1
end
print @sum
end
–SQL While循环 计算1~100之间奇数的和
begin
declare @sum int,@num int
set @sum=0
set @num=1
while @num<101
begin
set @num=@num+1
if((@num%2)=0)
continue
else
begin
set @sum=@sum+@num
if(@num=49)
break
end
end
print @sum
end
–根据查询的每个字段内容给予自定义数据–
select stuName,cursName,
case
when scScore>=85 then ‘优秀’
when scScore>=75 and scScore<85 then ‘良好’
when scScore>=60 and scScore<75 then ‘合格’
when scScore<60 then ‘不合格’
end
from score_tb sc,student_tb stu,course_tb cur where sc.scStuNo=stu.stuNo and cur.cursNo=sc.scCursNo
–自定义函数—
create function funSelectScore(@score float)
returns varchar(12)
as
begin
return
case
when @score>=85 then ‘优秀’
when @score>=75 and @score<85 then ‘良好’
when @score>=60 and @score<75 then ‘合格’
when @score<60 then ‘不合格’
end
end
–调用函数
select stuName,cursName,dbo.funSelectScore(scScore) –注意：调用函数是一定要加上 dbo.前缀
from score_tb sc,student_tb stu,course_tb cur where sc.scStuNo=stu.stuNo and cur.cursNo=sc.scCursNo
