Select column names and top 1 records along, dynamically - sql

Question

I was trying to select top 1 column value from the table to have a glimpse of the data, based on the output
(i.e. equivalently,
SELECT c.name FROM st.Name
This query retrieves column names and their data type along with the tables they're in. I am looking for an additional column that shows top 1 record from the columns.
SELECT
st.name 'Table Name',
c.name 'Column Name',
t.name 'Data Type'
FROM sys.columns c
INNER JOIN sys.types t ON c.user_type_id = t.user_type_id
LEFT OUTER JOIN sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
LEFT OUTER JOIN sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
LEFT OUTER JOIN sys.tables st ON st.object_id = i.object_id
I have been trying to use a dynamic sql, but as it should put the table name in a single quotation as a string, it couldn't work; when I try to avoid that, it just displays the declared variable.
Any idea is much appreciated. Thanks

Answer 1

So the way this works is basically creates a bunch of selects like:
SELECT 'dbo' AS [Schema Name]
, 'Table1' AS [Table Name]
, 'Id' AS [Column Name]
, 'bigint' AS [Data Type]
, (SELECT TOP 1 CONVERT(NVARCHAR(MAX), Id) FROM [dbo].[Table1]) AS [Top 1 Value]
UNION ALL
-- Another table
Values are converted into NVARCHAR(MAX) because column type in an union has to match and I guess that's the best bet.
Here goes:
DECLARE #query NVARCHAR(MAX) = ''
SELECT #Query +=
'SELECT ' + '''' + sch.name + '''' + ' AS [Schema Name],' + CHAR(13)+CHAR(10)
+ '''' + st.name + '''' + ' AS [Table Name],' + CHAR(13)+CHAR(10)
+ '''' + c.name + '''' + ' AS [Column Name],' + CHAR(13)+CHAR(10)
+ '''' + t.name + '''' + ' AS [Data Type],' + CHAR(13)+CHAR(10)
+ '(SELECT TOP 1 CONVERT(NVARCHAR(MAX), ' + c.name + ') FROM ' + QUOTENAME(sch.name) + '.' + QUOTENAME(st.name) + ') AS [Top 1 Value] ' + CHAR(13)+CHAR(10)
+ 'UNION ALL'+CHAR(13)+CHAR(10)
FROM sys.columns c
JOIN sys.types t ON c.user_type_id = t.user_type_id
JOIN sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
JOIN sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
JOIN sys.tables st ON st.object_id = i.object_id
JOIN sys.schemas sch ON sch.schema_id = st.schema_id
-- Get rid of trailing UNION ALL
SET #Query = LEFT(#Query, LEN(#Query) - LEN('UNION ALLxx'))
PRINT #query
EXEC sp_executesql #query
Consider running with TOP 10 or some such first to make sure it's producing the right results.

Answer 2

you could use a while loop with d sql
-
--drop table #temp
SELECT
CONCAT(s.name,'.',st.name) 'Table Name',
c.name 'Column Name',
t.name 'Data Type',
CAST(null AS datetime) as IND,
cast('' AS varchar(max)) data
INTO #temp
FROM sys.columns c
INNER JOIN sys.types t ON c.user_type_id = t.user_type_id
LEFT OUTER JOIN sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
LEFT OUTER JOIN sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
INNER JOIN sys.tables st ON st.object_id = i.object_id
INNER JOIN sys.schemas s ON s.schema_id = st.schema_id
declare
#TableName varchar(255),
#ColumnName Varchar(255),
#sql varchar(max)
WHILE (SELECT count(*) FROM #temp where IND is null) > 0
begin
SELECT TOP 1
#TableName = [Table Name]
,#ColumnName = [Column Name]
FROM #temp
WHERE IND IS NULL
SET #sql =
'update #temp
set data = (SELECT top 1 [' + #ColumnName + '] from ' + #TableName + '),
IND = getdate()
where [Table Name] = ''' + #TableName + ''' and [Column Name] = ''' + #ColumnName + ''''
exec(#sql)
end
SELECT *
FROM #temp