I have a question
I tried to google it but looks like they don't like *
I'm using SQL Server 2008.
I have the following database table:
P_Id ProductName UnitPrice UnitsInStock UnitsOnOrder
------------------------------------------------------------------------
1 Jarlsberg 10.45 16 15
2 Mascarpone Null 23 NULL
3 Gorgonzola 15.67 9 20
If I need to replace the null with a string I know I do :
SELECT ISNULL(UnitsOnOrder,'No Data') FROM tbl
Questions
How can I use ISNULL() with multi column names ?
is it possible to use it with *
Like
SELECT ISNULL(* , 'NO data') FROM tbl
I think this will be tricky because of the datatype, you can't pass string to INT datatype so how can I fix this too
Update
Okay if i use ISNULL() with a datatype of int it will return 0
which will be a value to me , how can i pass empty string instead ?
You can use ISNULL multiple times in the same SQL statement for different columns, but you must write it separately for each column:
SELECT
ISNULL(ProductName, 'No Data') AS ProductName,
ISNULL(CAST(UnitPrice AS NVARCHAR), 'No Data') AS UnitPrice,
ISNULL(CAST(UnitsInStock AS NVARCHAR), 'No Data') AS UnitsInStock,
ISNULL(CAST(UnitsOnOrder AS NVARCHAR), 'No Data') AS UnitsOnOrder
FROM tbl
If you are building a dynamic SQL query, you could theoretically gather a list of columns in the table and generate a query with ISNULL on each one. For example:
DECLARE #SQL nvarchar(max)
SET #SQL = 'SELECT '
SELECT #SQL = #SQL + 'ISNULL(CAST([' + sc.name + '] AS NVARCHAR), ''No Data'') AS [' + sc.name + '],'
FROM sys.objects so
INNER JOIN sys.columns sc ON sc.object_id = so.object_id
WHERE so.name = 'tbl'
-- Remove the trailing comma
SELECT #SQL = LEFT(#SQL, LEN(#SQL) - 1) + ' FROM tbl'
EXEC sp_sqlexec #SQL
This code has problems when converting some column types like timestamps to an nvarchar, but it illustrates the technique.
Note that if you had another column that should be returned if a value is null, you could use the COALESCE expression like this:
SELECT COALESCE(ProductName, P_Id) AS Product...
Try this...
ISNULL (COALESCE (column1, column2), 'No Data')
You would need to include all column names though, you can't use *
COALESCE returns the first non-null value in its argument list so if they are all null it will return null
Related
I am trying to get the dynamic column names from the table using the 'INFORMATION_SCHEMA.COLUMNS' Following is the query.
Select COLUMN_NAME into #TempTable
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = 'MyTable'
Result:
COLUMN_NAME
Person_ID
Person_Name
Person_Address
Wanting to Do:
Select * from MyTable where Person_ID = 1
What can be the ways to use the Person_ID from 1st query to the second query?
You can use dynamic SQL to execute this via the EXEC command.
Build a VARCHAR string for your query based on the dynamic column names you are getting from your first query, then EXEC on the string you have created.
You have not provided enough information on exactly what columns you need in your WHERE clause, or how you determine which ones, but dynamic SQL seems to be what you need here.
if you are trying to do something like this
select * from [table] where [col] =#param
then you can use query like below
declare #query nvarchar(max)
select
#query='select * from '+t.name +
' where '+c.name + ' ='+
case
when c.name ='Person_ID' then '1'
when c.name ='Someother_ID' then '10'
else c.name
end
from sys.tables t join sys.columns c
on c.object_id=t.object_id
and t.name ='MyTable'
exec( #query)
I am dealing with a huge list of columns (around 50) where i only need to group by one column. Is there anyway in SQL Server i can aggregate the columns by something such as
SELECT MAX(*)
FROM View1
GROUP BY Column1
instead of having to go through each one and specify an aggregate function. I have had a look online but cant find anything. Is there any advice or guidance someone can give me or is it just a case of going through each row?
Thanks
You can build query you need using system tables:
DECLARE #ViewName sysname = N'View1',
#query nvarchar(max),
#Column sysname = 'Column1'
SET #query = N'SELECT ' + #Column + ',' + CHAR(10)
SELECT #query = #query + N'MAX('+c.[name]+') as '+c.[name]+',' + CHAR(10)
FROM sys.views v
INNER JOIN sys.columns c
ON v.[object_id] = c.[object_id]
WHERE v.[name] = #ViewName AND c.[name] != #Column
SET #query = STUFF(#query,LEN(#query)-1,1,'') + 'FROM '+#ViewName + CHAR(10) + 'GROUP BY ' + #Column
PRINT #query
Output will be:
SELECT Column1,
MAX(Column2) as Column2,
MAX(Column3) as Column3,
...
MAX(ColumnN) as ColumnN
FROM View1
GROUP BY Column1
You can Ctrl+C Ctrl+V on new query window and execute, or execute it right here with:
EXEC (#query)
In case of tables - you need to use sys.tables
In case if view or table is not in default schema - you need to specify it manually.
SET #query = STUFF(#query,LEN(#query)-1,1,'') + 'FROM dbo.'+#ViewName + CHAR(10) + 'GROUP BY ' + #Column
No. Unfortunately, you're going to have to write out the columns.
If you need max value from different columns you can try as below
Select max(yourcolumn) from
(
Select col1 from yourtable
union all Select col2 from yourtable
union all Select col3 from yourtable
...
) a
No, you can not use max(*).
You will have to give a column name in max function like below
select max(column_name) from table_name;
You cannot write select max(*). This results in the error Incorrect syntax near '*'. Instead, you will need to specify the columns.
One way to get the maximum of multiple columns is to unpivot the table. An efficient way to do this is to use cross apply to generate separate row values for each column.
For example, the code below finds the maximum value across 3 different columns in all of the rows:
declare #test table
(
id int primary key clustered,
value1 int,
value2 int,
value3 int
)
insert into #test (id, value1, value2, value3)
values (1, 100, 0, 0), (2, 0, 50, 0), (3, 0, 0, 25)
select max(TestValue) -- returns 100
from #test
cross apply
(
values(value1),(value2), (value3)
) TestValues (TestValue)
Say I have a table called:
TableA
The following columns exist in the table are:
Column1, Column2, Column3
what I am trying to accomplish is to see how many records are not null.
to do this I have the following case statement:
sum(Case when Column1 is not null then 1 else 0 end)
What I want is the above case statement for every table that exists from a list provided and to be run for each columns that exists in the table.
So for the above example the case statment will run for Column1, Column2 and Column3 as there are 3 columns in that particular table etc
But I want to specfiy a list of tables to loop through executing the logic above
create procedure tab_cols (#tab nvarchar(255))
as
begin
declare #col_count nvarchar(max) = ''
,#col nvarchar(max) = ''
select #col_count += case ORDINAL_POSITION when 1 then '' else ',' end + 'count(' + QUOTENAME(COLUMN_NAME,']') + ') as ' + QUOTENAME(COLUMN_NAME,']')
,#col += case ORDINAL_POSITION when 1 then '' else ',' end + QUOTENAME(COLUMN_NAME,']')
from INFORMATION_SCHEMA.COLUMNS
where TABLE_NAME = #tab
order by ORDINAL_POSITION
declare #stmt nvarchar(max) = 'select * from (select ' + #col_count + ' from ' + #tab + ') t unpivot (val for col in (' + #col + ')) u'
exec sp_executesql #stmt
end
Wouldn't it be easy as this?
SELECT AccountID
,SUM(Total) AS SumTotal
,SUM(Profit) AS SumProfit
,SUM(Loss) AS SumLoss
FROM tblAccount
GROUP BY AccountID
If I understand this correctly you want to get the sums, but not for all rows in one go but for each accountID separately. This is what GROUP BY is for...
If ever possible try to avoid loops, cursors and other procedural approaches...
UPDATE: Generic approach for different tables
With different tables you will - probably - need exactly the statement I show above, but you'll have to generate it dynamically and use EXEC to execute it. You can go through INFORMATION_SCHEMA.COLUMNS to get the columns names...
But:
How should this script know generically, which columns should be summed up? You might head for data_type like 'decimal%' or similar...
What about the other columns and their usage in GROUP BY?
How would you want to place aliases
How do you want to continue with a table of unknown structure?
To be honest: I think, there is no real-generic-one-for-all approach for this...
Please help me with this. I am totally stuck. I have coders block or something.
I have the following table
ID Name Cost Included
---- ---------- ------- ----------
1 Package1 10.00 Yes
2 Package2 20.00 No
3 Package3 20.00 Yes
I would like to crosstab this information, to display like the following example,there will be more columns in the table.
Type Package1 Package2 Package3
----- ------------ ----------- ----------
Name Package1 Package2 Package3
Cost 10.00 20.00 30.00
Included Yes No Yes
It seems to me that you are trying to build a product comparison list. If this is true, you might unpivot the table first and then join individual records together.
The 'transponded' part unpivots the columns. All columns must be of compatible types or converted to one. I choose varchar(100). transponded returns table with three columns, ID from ProductInfo, Type as column name and Value as value of corresponding column.
Select part joins together info on as many product as demanded by adding another left join transponded tn on t1.Type = tnType and tn.ID = #parametern. This part seems as a hassle, but when I tried to do this part with pivot I failed to get column in proper order - pivot sorted names in Type. It would however demand dynamic sql generation. This solution is fixed providing that you add enough joins for maximum products you wish to compare at once. I belive it would not be over 5.
=1, =2 and =3 should be replaced by parameters. The query should be hosted in stored procedure.
; with transponded as
(
select ID, Type, Value
from
(
select ID,
Name,
cast (Cost as varchar(100)) Cost,
cast (case when Included = 1 then 'Yes' else 'No' end as varchar(100)) Included
from ProductInfo
) p
unpivot (Value for Type in (Name, Cost, Included) ) a
)
select t1.Type,
t1.Value Product1,
t2.Value Product2,
t3.Value Product3
from transponded t1
left join transponded t2
on t1.Type = t2.Type
and t2.id = 2
left join transponded t3
on t1.Type = t3.Type
and t3.id = 3
where t1.id = 1
In short, transpond one record at time and join to another transponded record by Type column.
Oh, and here is a Sql Fiddle playground.
There is no easy way to do this, as the pivot will need to be aggregated by column. Given that adding columns to the input table would cause a maintenance issue where these values will not be presented to the output until the code is changed wherever it is used, I'd say you're probably best doing it once with a stored procedure, which will dynamically generate the output you're looking for based on the schema of the input table.
I have demonstrated how this can be done, using the data you have supplied. This data is stored in a temp table (not #temp, because the stored proc won't work with temporary tables), populated thus:
CREATE TABLE temp (
_key int,
package_name varchar(50),
cost float,
included bit
)
INSERT INTO temp VALUES(1,'Package1', 10.00, 1)
INSERT INTO temp VALUES(2,'Package2', 20.00, 0)
INSERT INTO temp VALUES(3,'Package3', 20.00, 1)
The stored procedure retrieves a list of values based on the #pivot_field parameter, and uses these values as a column list to be inserted after the "Type" field. It then unions the pivot field and all other fields together to generate the rows, pivoting one column at a time. The procedure is as follows:
CREATE PROCEDURE usp_get_pivot (#table_name nvarchar(255), #pivot_field nvarchar(255)) AS
BEGIN
CREATE TABLE #temp (val nvarchar(max))
DECLARE #sql NVARCHAR(MAX), #cols NVARCHAR(MAX), #col NVARCHAR(255)
SET #sql = 'SELECT DISTINCT ' + #pivot_field + ' FROM ' + #table_name
INSERT INTO #temp EXEC sp_executesql #sql;
SET #cols = (SELECT '[' + val + '],' FROM #temp FOR XML PATH(''))
SET #cols = SUBSTRING(#cols, 1, LEN(#cols)-1)
SET #SQL = N'SELECT ''' + #pivot_field + ''' as [type], *
FROM (SELECT ' + #pivot_field + ', ' + #pivot_field + ' as ' + #pivot_field + '1 FROM ' + #table_name + ') AS source_table
PIVOT (max(' + #pivot_field + '1) FOR ' + #pivot_field + ' IN (' + #cols + ')) AS pivot_table'
DECLARE csr CURSOR FOR
SELECT c.name FROM sys.columns c, sys.objects o
WHERE c.object_id = o.object_id AND o.name = #table_name
AND c.name <> #pivot_field
ORDER BY column_id
OPEN csr
FETCH NEXT FROM csr INTO #col
WHILE ##FETCH_STATUS = 0
BEGIN
SET #sql = #sql + ' UNION ALL
SELECT ''' + #col + ''' as [type], *
FROM (SELECT ' + #pivot_field + ', CAST(' + #col + ' AS VARCHAR) AS ' + #col + ' FROM ' + #table_name + ') AS source_table
PIVOT (max(' + #col + ') FOR ' + #pivot_field + ' IN (' + #cols + ')) AS pivot_table'
FETCH NEXT FROM csr INTO #col
END
CLOSE csr
DEALLOCATE csr
DROP TABLE #temp
EXEC sp_executesql #sql
END
You should be able to simply copy and paste the procedure into management studio, create the data is shown above and execute the procedure with:
EXEC usp_get_pivot 'temp', 'package_name'
If number of packages is not static there is no option for you I think. PIVOT clause can produce only static/defined number of columns.
You may do some table-to-table rewriting using multiple statements - but still you have to face with static number of columns.
But you may set it to for example to 10 and then display up to 10 packages, having NULL-s in rest of columns if there are less packages.
You may also use dynamic SQL to have dynamic number of columns - but it will be a headache.
If you're going to export this data to Excel - do not pivot it at SQL - do a transposition in Excel (it's under "paste special").
Basically what i have at this stage is the following.
SELECT [Type],
MAX(Beginner) AS [Beginner],
MAX(Intermediate) AS [Intermediate],
MAX(Advanced) AS [Advanced]
FROM
(
SELECT
'Name' AS TYPE,
CASE WHEN Name='Beginner' THEN Name END AS [Beginner],
CASE WHEN Name='Intermediate' THEN Name END AS [Intermediate],
CASE WHEN Name='Advanced' THEN Name END AS [Advanced]
FROM Administration.Package
UNION ALL
SELECT
'Price' AS TYPE,
CASE WHEN Name='Beginner' THEN CAST(Price AS VARCHAR) END AS [Beginner],
CASE WHEN Name='Intermediate' THEN CAST(Price AS VARCHAR) END AS [Intermediate],
CASE WHEN Name='Advanced' THEN CAST(Price AS VARCHAR) END AS [Advanced]
FROM Administration.Package
)A
GROUP BY [Type]
But it does not feel right to have the union for each and every column.
I'm just starting to learn T-SQL and could use some help in understanding what's going on in a particular block of code. I modified some code in an answer I received in a previous question, and here is the code in question:
DECLARE #column_list AS varchar(max)
SELECT #column_list = COALESCE(#column_list, ',') +
'SUM(Case When Sku2=' + CONVERT(varchar, Sku2) +
' Then Quantity Else 0 End) As [' +
CONVERT(varchar, Sku2) + ' - ' +
Convert(varchar,Description) +'],'
FROM OrderDetailDeliveryReview
Inner Join InvMast on SKU2 = SKU and LocationTypeID=4
GROUP BY Sku2 , Description
ORDER BY Sku2
Set #column_list = Left(#column_list,Len(#column_list)-1)
Select #column_list
----------------------------------------
1 row is returned:
,SUM(Case When Sku2=157 Then Quantity Else 0 End) As [157 -..., SUM(Case ...
The T-SQL code does exactly what I want, which is to make a single result based on the results of a query, which will then be used in another query.
However, I can't figure out how the SELECT #column_list =... statement is putting multiple values into a single string of characters by being inside a SELECT statement. Without the assignment to #column_list, the SELECT statement would simply return multiple rows. How is it that by having the variable within the SELECT statement that the results get "flattened" down into one value? How should I read this T-SQL to properly understand what's going on?
In SQL Server:
SELECT #var = #var + col
FROM TABLE
actually concatenates the values. It's a quirks mode (and I am unable at this time to find a reference to the documentation of feature - which has been used for years in the SQL Server community). If #var is NULL at the start (i.e. an uninitialized value), then you need a COALESCE or ISNULL (and you'll often use a separator):
SELECT #var = ISNULL(#var, '') + col + '|'
FROM TABLE
or this to make a comma-separated list, and then remove only the leading comma:
SELECT #var = ISNULL(#var, '') + ',' + col
FROM TABLE
SET #var = STUFF(#var, 1, 1, '')
or (courtesy of KM, relying on NULL + ',' yielding NULL to eliminate the need for STUFF for the first item in the list):
SELECT #var = ISNULL(#var + ',', '') + col
FROM TABLE
or this to make a list with a leading, separated and trailing comma:
SELECT #var = ISNULL(#var, ',') + col + ','
FROM TABLE
You will want to look into the COALESCE function. A good article describing what is happening can be seen here.