SQL-Server getting list of columns that doesn't contains any value

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When having table with large number of columns, it may be helpful to find if there are columns that doesn't contains any value.

You can use the following query to achieve this (Just replace 'dbo.MyTable' with your table name)

Query steps:
1- Getting all columns count using one select query and giving an alias the original column name for each count column
2- Pivoting Result Table into a Temp table
3- Selecting Columns that have a Count = 0 from Temp Table

DECLARE @strTablename  varchar(100) = 'dbo.MyTable'
DECLARE @strQuery  varchar(max) = ''
DECLARE @strUnPivot as varchar(max) = ' UNPIVOT ([Count] for [Column] IN ('

CREATE TABLE ##tblTemp([Column] varchar(50), [Count]  Int)

SELECT @strQuery = ISNULL(@strQuery,'') + 'Count([' + name + ']) as [' + name + ']  ,' from sys.columns where object_id = object_id(@strTablename) and is_nullable = 1
SELECT @strUnPivot = ISNULL(@strUnPivot,'') + '[' + name + '] ,' from sys.columns where object_id = object_id(@strTablename) and is_nullable = 1


SET @strQuery = 'SELECT [Column],[Count] FROM ( SELECT ' + SUBSTRING(@strQuery,1,LEN(@strQuery) - 1) + ' FROM ' + @strTablename + ') AS p ' + SUBSTRING(@strUnPivot,1,LEN(@strUnPivot) - 1) + ')) AS unpvt '

INSERT INTO ##tblTemp EXEC (@strQuery)

SELECT [Column] from ##tblTemp Where [Count] =0

DROP TABLE ##tblTemp
And also you can use the following query to select only columns that contains at least one value

Query steps:
1- Getting all columns count using one select query and giving an alias the original column name for each count column
2- Pivoting Result Table into a Temp table
3- Creating Select query by selecting the rows that have a Count > 0 from Temp Table
4- Executing this query

DECLARE @strTablename  varchar(100) = 'dbo.MyTable'
DECLARE @strQuery  varchar(max) = ''
DECLARE @strSecondQuery  varchar(max) = 'SELECT '
DECLARE @strUnPivot as varchar(max) = ' UNPIVOT ([Count] for [Column] IN ('

CREATE TABLE ##tblTemp([Column] varchar(50), [Count]  Int)

SELECT @strQuery = ISNULL(@strQuery,'') + 'Count([' + name + ']) as [' + name + ']  ,' from sys.columns where object_id = object_id(@strTablename) and is_nullable = 1
SELECT @strUnPivot = ISNULL(@strUnPivot,'') + '[' + name + '] ,' from sys.columns where object_id = object_id(@strTablename) and is_nullable = 1


SET @strQuery = 'SELECT [Column],[Count] FROM ( SELECT ' + SUBSTRING(@strQuery,1,LEN(@strQuery) - 1) + ' FROM ' + @strTablename + ') AS p ' + SUBSTRING(@strUnPivot,1,LEN(@strUnPivot) - 1) + ')) AS unpvt '

INSERT INTO ##tblTemp EXEC (@strQuery)

SELECT @strSecondQuery = @strSecondQuery + '[' + [Column] + '],'  from ##tblTemp where [Count] > 0

DROP TABLE ##tblTemp

SET @strSecondQuery = SUBSTRING(@strSecondQuery,1,LEN(@strSecondQuery) - 1) + ' FROM ' + @strTablename

EXEC (@strSecondQuery)

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