How to conduct field statistics?-CodePudding

Id name subj score
1 a language 88
2 a math 89
3 b language 89
()
A SQL shows: calculate the score field in 89 the number of occurrences of, and in the field most shown below, in () place, and can automatically change according to the records

CodePudding user response:

 

If not object_id (N 'tempdb for.. # a ') is null 
Drop table # a 
Go 
The create table # a (
Id int, 
[name] nvarchar (10), 
Subj nvarchar (10), 
Score nvarchar (10) 
) 
Go 
Insert # a 
Select 1, 'a', 'language', '88' union all 
Select 2, 'a', 'mathematics',' 89 'union all 
Select 3, 'b', 'English', '89' 
Go 
Select * from # a 
Go 

Select * from # a 
The union 
Select 4, 'a', ' ', the count (*) from # where a score=89

CodePudding user response:

The

reference 1/f, one tree forest _ response:

 

If not object_id (N 'tempdb for.. # a ') is null 
Drop table # a 
Go 
The create table # a (
Id int, 
[name] nvarchar (10), 
Subj nvarchar (10), 
Score nvarchar (10) 
) 
Go 
Insert # a 
Select 1, 'a', 'language', '88' union all 
Select 2, 'a', 'mathematics',' 89 'union all 
Select 3, 'b', 'English', '89' 
Go 
Select * from # a 
Go 

Select * from # a 
The union 
Select 4, 'a', ' ', the count (*) from # where a score=89

 

- can also be changed to the following 4 this 
Select * from # a 
The union 
Select Max (id) + 1, "', ', the count (*) from # where a score=89

CodePudding user response:

Every step can explain? See not too understand

CodePudding user response:

The

reference 3 floor qq_26600333 response:

can explain each step? See not too understand

 


- whether the database is # a temporary table, if there is a delete 
If not object_id (N 'tempdb for.. # a ') is null 
Drop table # - this is a drop the temporary table 
Go - go end can be understood as a 
# - create a temporary table 
The create table # a (
Id int, 
[name] nvarchar (10), 
Subj nvarchar (10), 
Score nvarchar (10) 
) 
Go 
- to the temporary table insert data 
Insert # a 
Select 1, 'a', 'language', '88' union all 
Select 2, 'a', 'mathematics',' 89 'union all 
Select 3, 'b', 'English', '89' 
Go 
- query temporary table 
Select * from # a 
Go 
- joining together the query 
Select * from # - a first query out all data 
The union - using keywords for Mosaic 
Select Max (id) + 1, "', ', the count (*) from # where a score=89

CodePudding user response:

Still don't fully understand, but thank god