I have a table with three columns :- name, col1, col2
I need to create another table with col1 as columns and col2 as values. Can someone give me an idea.
This is the source:
Name col1 col2
details Company Microsoft
details Employees 300
details City New York
details2 Company Apple
details2 Employees 450
details2 City Boston
I need a table for details like this
Company Employees City
Microsoft 300 NewYork
And another table for details2 like this:
Company Employees City
Apple 450 Boston
You can convert your One column values as Table Column and Second column values as Rows like this way
First Approach:- SAMPLE SQL FIDDLE
Select
MAX(case when col1 = 'Company' then col2 end) Company,
MAX(case when col1 = 'Employee' then col2 end) Employee,
MAX(case when col1 = 'City' then col2 end) City
From test
Group By name
EDIT
Second Approach :- SQL FIDDLE
DECLARE #QUERY NVARCHAR(MAX), #Soucecolumn VARCHAR(MAX)
SET #Soucecolumn = STUFF((SELECT distinct ',[' + [col1 ] + ']' FROM test FOR XML PATH('')),1,1,'')
SET #QUERY = 'SELECT ' + #Soucecolumn + ' FROM test PIVOT (MAX(col2) FOR [col1 ] IN (' + #Soucecolumn + ')) AS pvt'
exec sp_executesql #QUERY
Related
I'm working with a legacy DB that has a table that houses field names from other tables.
So I have this structure:
Field_ID | Field_Name
*********************
1 | Col1
2 | Col2
3 | Col3
4 | Col4
and I need to pull a list of this field metadata along with the values of that field for a given user. So I need:
Field_ID | Field_Name | Value
1 | Col1 | ValueOfCol1onADiffTable
2 | Col2 | ValueOfCol2onADiffTable
3 | Col3 | ValueOfCol3onADiffTable
4 | Col4 | ValueOfCol4onADiffTable
I'd like to use the Field_Name in a subquery to pull that value, but can't figure out how to get SQL to evaluate Field_Name as a column in the sub-query.
So something like this:
select
Field_ID
,Field_Name
,(SELECT f.Field_Name from tblUsers u
where u.User_ID = #userId) as value
from
dbo.tblFields f
But that just returns Field_Name in the values column, not the value of it.
Do I need to put the sub-query in a separate function and evaluate that? Or some kind of dynamic SQL?
In SQL server this would require dynamic SQL and UNPIVOT notation.
see working demo
create table tblFields (Field_ID int ,Field_Name varchar(10));
insert into tblFields values
(1,'Col1')
,(2,'Col2')
,(3,'Col3')
,(4,'Col4');
declare #userId int
set #userId=1
create table tblUsers (User_ID int, col1 varchar(10),col2 varchar(10));
insert into tblUsers values
(1, 10,100),
(2,20,200);
declare #collist varchar(max)
declare #sqlquery varchar(max)
select #collist= COALESCE(#collist + ', ', '') + Field_Name
from dbo.tblFields
where exists (
select * from sys.columns c join sys.tables t
on c.object_id=t.object_id and t.name='tblUsers'
and c.name =Field_Name)
select #sqlquery=
' select Field_ID ,Field_Name, value '+
' from dbo.tblFields f Join '+
' ( select * from '+
'( select * '+
' from tblUsers u '+
' where u.User_ID = '+ cast(#userId as varchar(max)) +
' ) src '+
'unpivot ( Value for field in ('+ #collist+')) up )t'+
' on t.field =Field_Name'
exec(#sqlquery)
I have a Question table, which has a unknown number of questions.(first table in the figure)
I also have an AnswerSheet table, which records student's answer to question.(second table in the figure)
Create table Question
(
Id int,
Text nvarchar(50),
PRIMARY KEY (Id)
)
Create table AnswerSheet
(
StudentId int,
QuestionId int,
Answer nvarchar(50),
PRIMARY KEY (StudentId,QuestionId),
FOREIGN KEY (QuestionId) REFERENCES Question (Id)
)
insert into Question
values(1,'What''s your age'),
(2,'What''s your gender'),
(3,'When do you go home'),
....
insert into AnswerSheet
values(500,1,'20'),
(500,2,'Male'),
(500,3,'5:00pm'),
(501,1,'50'),
(502,2,'I don''t know##'),
....
How do I write a SQL to generate a table like this?
StudentId What's your age What's your gender When do you go home ...
--------- ---------------- ------------------- -------------------
500 20 Male 5:00pm ...
501 50 NULL NULL
502 NULL I don''t know## NULL ...
I feel Pivot is promising but I'm not sure how to use it especially PIVOT requires an aggreation function but my data are not numbers.
Assuming you wanted to go Dynamic
Example
Declare #SQL varchar(max) = Stuff((Select ',' + QuoteName(Text) From Question Order by ID For XML Path('')),1,1,'')
Select #SQL = '
Select *
From (
Select StudentID
,Col = B.Text
,Value = A.Answer
From AnswerSheet A
Join Question B on A.QuestionID=B.ID
) A
Pivot (max(Value) For [Col] in (' + #SQL + ') ) p'
Exec(#SQL);
Returns
StudentID What's your age What's your gender When do you go home
500 20 Male 5:00pm
501 50 NULL NULL
502 NULL I don't know## NULL
If it Helps, the Generated SQL Looks Like This
Select *
From (
Select StudentID
,Col = B.Text
,Value = A.Answer
From AnswerSheet A
Join Question B on A.QuestionID=B.ID
) A
Pivot (max(Value) For [Col] in ([What's your age],[What's your gender],[When do you go home]) ) p
I know this question is answered by accepted one, but I hope this approach helps others.
simply you can achieve your goal without using Pivot, via using Group by as next:-
Select b.StudentId,
Min(Case a.text When 'What''s your age' Then b.answer End) 'What''s your age',
Min(Case a.text When 'What''s your gender' Then b.answer End) 'What''s your gender',
Min(Case a.text When 'When do you go home' Then b.answer End) 'When do you go home'
from Question a inner join AnswerSheet b
on a.id = b.Questionid
Group By StudentId
and you mentioned unknown number of questions, so the next code for dynamic:-
DECLARE #DynamicQuestions VARCHAR(8000)
SELECT #DynamicQuestions = Stuff(
(SELECT N' Min(Case a.text When''' + replace (Text,'''','''''')
+ ''' Then b.answer End) '''
+ replace (Text,'''','''''') + ''','
FROM Question FOR XML PATH(''),TYPE)
.value('text()[1]','nvarchar(max)'),1,1,N'')
select #DynamicQuestions =
left(#DynamicQuestions,len(#DynamicQuestions)-1) -- for Removing last comma
exec ('Select b.StudentId, '+ #DynamicQuestions +
'from Question a inner join AnswerSheet b
on a.id = b.Questionid
Group By StudentId' )
Result:-
StudentId What's your age What's your gender When do you go home
500 20 Male 5:00pm
501 50 NULL NULL
502 NULL I don't know## NULL
In the image above, i have shown table structure i use to store result of student. However I need to select data in such a manner such that depending on particular FEID(examination ID),
I get marks obtained and subID of single student in single row. Something like below:
FEID SubID1 MarksObtained SubID2 MarksObtained SubID3 MarksObtained StdID
2 1 0 2 0 3 0 50
2 1 45 2 45 3 45 51
Result Column wont affect outcome as for a particular stdID and FEID it remains same for no matter how many SubID are there.
Basically I am storing each subject marks in single row and subjects are can be any number( more than 3 as in this case) , which is not known before hand. But for each I create one row to enter its marks
I tried sytax below .
DECLARE #cols nvarchar(MAX);
--get the list of subids from the table
SELECT #cols = SubjectName from tbSubjects where SubID IN(select distinct SubID from tbFinalMarks);
Declare #sql nvarchar(MAX) = 'SELECT StdId, FEID, ' + #cols + 'FROM
(
SELECT * FROM tbFinalMarks
)t
PIVOT
(
MAX(MarksObtained) FOR SubId IN (' + #cols + ')
)p';
Something like this will do it. It will also dynamically add new columns for new sub ids without you needing to worry about it.
DECLARE #cols nvarchar(MAX);
--get the list of subids from the table
SELECT #cols = COALESCE(#cols + ',', '') + '[' + CAST(SubId AS nvarchar) + ']' FROM (SELECT DISTINCT SubId FROM table);
Declare #sql nvarchar(MAX) = 'SELECT StdId, FEID, ' + #cols + 'FROM
(
SELECT * FROM table
)t
PIVOT
(
MAX(MarksObtained) FOR SubId IN (' + #cols + ')
)p';
EXECUTE sp_executesql #sql;
Although you can use pivot, I think the explicit aggregation approach is easier to construct:
select feid,
1 as SubId_1,
max(case when SubId = 1 then MarksObtained end) as MarksObtained_1,
2 as SubId_2,
max(case when SubId = 2 then MarksObtained end) as MarksObtained_2,
3 as SubId_3,
max(case when SubId = 3 then MarksObtained end) as MarksObtained_3,
stdid
from table t
group by feid, stdid;
I have a trick problem with a pivot table to make:
I have a table which looks like:
id table object name type nvarchar date int bit
1 1 2 name 1 tables NULL NULL NULL
2 1 2 name 1 columns NULL NULL NULL
3 1 2 name 1 datatypes NULL NULL NULL
4 1 2 name 1 _users NULL NULL NULL
1 1 3 active 3 NULL NULL NULL 1
2 1 3 active 3 NULL NULL NULL 1
3 1 3 active 3 NULL NULL NULL 1
4 1 3 active 3 NULL NULL NULL 1
the output should look like:
id name active
1 tables 1
2 columns 1
3 datatypes 1
4 _users 1
Based upon the "type" I should put the correct data from the column in it, these columns are formated in nvarchar, bit, datetime, int, ect.
The "id" is the row id, the "name, active" comes from the name column and the values from nvarchar, date, int and bit columns.
UPDATE: the columns like nvarchar, date, int and bit (and most other SQL formats) are actually contain this type of data. The column "type" gives which column contains the data to being used, so if "type" is "1", than I want to use the "nvarchar" if "type" is "3" than I want to use the "bit" which contains really a bit and not a nvarchar. In the Pivot I want to have the bit under "active" column, if I have in the example a 3th column (name) for example "activation_date" I want to see a third column with the value (type = 2) from the date column.
I am lost in this, please help
Assuming there's only one not null column for each row:
with cte as (
select
id,
name,
coalesce(
[nvarchar],
convert(nvarchar(max), [date], 120),
cast([int] as nvarchar(max)),
cast([bit] as nvarchar(max))
) as value
from Table1 as t
)
select
id,
max(case when [name] = 'name' then value end) as [name],
max(case when [name] = 'active' then value end) as [active]
from cte
group by id
sql fiddle demo
But I must warn you, this types of database schema is not best way to use SQL.
If you want to do this dynamically without hardcoding columns:
declare #stmt nvarchar(max)
select #stmt =
isnull(#stmt + ', ', '') +
'max(case when [name] = ''' + name + ''' then value end) as ' + quotename([name])
from (select distinct [name] from Table1) as t
select #stmt = '
with cte as (
select
id,
name,
coalesce(
[nvarchar],
convert(nvarchar(max), [date], 120),
cast([int] as nvarchar(max)),
cast([bit] as nvarchar(max))
) as value
from Table1 as t
)
select
id, ' + #stmt + '
from cte
group by id
'
exec sp_executesql
#stmt = #stmt
sql fiddle demo
If you have some Mapping table like this:
name value
--------------------
name nvarchar
active bit
you can use this query:
declare #stmt nvarchar(max)
select #stmt =
isnull(#stmt + ', ', '') +
'max(case when [name] = ''' + name + ''' then [' + value + '] end) as ' + quotename([name])
from Mapping
select #stmt = '
select
id, ' + #stmt + '
from Table1
group by id
'
exec sp_executesql
#stmt = #stmt
sql fiddle demo
How can I change this table
Name subject Mark
Aswin physics 100
Aswin chemistry 300
Aswin maths 200
Into
Aswin Physics 100 Chemistry 300 Maths 200
Any one please help me.
you can use PIVOT operator to do this job in sql server.
check these links link1 and link2 they will show how to change row into column.
hope this helps you!
SQLFiddle demo
select Name,
sum(CASE
when [subject]='physics' then Mark
end) as Physics,
sum(CASE
when [subject]='chemistry' then Mark
end) as chemistry,
sum(CASE
when [subject]='maths' then Mark
end) as maths
from t group by Name
Or if you need it in one line:
SQLFiddle demo
SELECT
t1.name,
MemberList = substring((SELECT ( ', ' + subject+' - '+
cast(Mark as varchar(100)) )
FROM t t2
WHERE t1.name = t2.name
ORDER BY
name,
subject
FOR XML PATH( '' )
), 3, 1000 )FROM t t1
GROUP BY name
You need to use SQL Pivoting, check the examples at SQL SERVER – PIVOT and UNPIVOT Table Examples. Using Sql Pivoting you can change the rows to columns and Unpivoting is for columns to rows conversion.
Please note: I am checking if I can provide you exact script but for now the link would help you out.
UPDATE
Code example
Though I have not tested this with actual data but it parses fine.
-- Pivot Table ordered by Name of Student
SELECT Name, Physics, Chemistry, Maths
FROM (
SELECT Name, Subject, Mark
FROM Student) up
PIVOT (SUM(Mark) FOR Student IN (Physics, Chemistry, Maths)) AS pvt
ORDER BY Name
-- Result should be something like
----------------------------------
Name Physics Chemistry Maths
----------------------------------
Aswin 100 300 200
----------------------------------
For creating pivot you need to know the actual rows values to convert into columns.
I have wrote before about dynamic pivoting here if you find it useful.
It is not exactly clear if you want this data in separate columns or in one column.
If you want this in separate columns, then you can apply the PIVOT function which became available in SQL Server 2005.
If you know all of the values that you want to transform or have a limited number, then you can hard-code the query:
select *
from
(
select name, subject +' '+ cast(mark as varchar(9)) as sub_mark,
'Subject_'+cast(row_number() over(partition by name
order by subject) as varchar(10)) col_name
from subjects
) s
pivot
(
max(sub_mark)
for col_name in (Subject_1, Subject_2, Subject_3)
) piv;
See SQL Fiddle with Demo. You will notice that I did this slightly different from the other pivot answer. I placed both the subject/mark in the same column with a column name of Subject_1, etc.
If you have an unknown number of values, then you can use dynamic sql:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT distinct ',' + QUOTENAME('Subject_'+cast(row_number() over(partition by name
order by subject) as varchar(10)))
from subjects
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT name,' + #cols + ' from
(
select name, subject +'' ''+ cast(mark as varchar(9)) as sub_mark,
''Subject_''+cast(row_number() over(partition by name
order by subject) as varchar(10)) col_name
from subjects
) x
pivot
(
max(sub_mark)
for col_name in (' + #cols + ')
) p '
execute(#query)
See SQL Fiddle with Demo. The dynamic sql version will increase in the number of columns if a name has more than 3 subjects.
The result of both queries is:
| NAME | SUBJECT_1 | SUBJECT_2 | SUBJECT_3 |
---------------------------------------------------
| Aswin | chemistry 300 | maths 200 | physics 100 |