SQL Script for creating test sample data from source table - sql

Question

I've created the script below to be able to quickly create a minimal reproducible example for other questions in general.
This script uses an original table and generates the following PRINT statements:
DROP and CREATE a temp table with structure matching the original table
INSERT INTO statement using examples from the actual data
I can just add the original table name into the variable listed, along with the number of sample records required from the table. When I run it, it generates all of the statements needed in the Messages window in SSMS. Then I can just copy and paste those statements into my posted questions, so those answering have something to work with.
I know that you can get similar results in SSMS through Tasks>Generate Scripts, but this gets things down to the minimal amount of code that's useful for posting here without all of the unnecessary info that SSMS generates automatically. It's just a quick way to create a reproduced version of a simple table with actual sample data in it.
Unfortunately the one scenario that doesn't work is if I run it on very wide tables. It seems to fail on the last STRING_AGG() query where it's building the VALUES portion of the INSERT. When it runs on wide tables, it returns NULL.
Any suggestions to correct this?
EDIT: I figured out the issue I was having with UNIQUEIDENTIFIER columns and revised the query below. Also included an initial check to make sure the table actually exists.
/* ---------------------------------------
-- For creating minimal reproducible examples
-- based on original table and data,
-- builds the following statements
-- -- CREATE temp table with structure matching original table
-- -- INSERT statements based on actual data
--
-- Note: May not work for very wide tables due to limitations on
-- PRINT statements
*/ ---------------------------------------
DECLARE #tableName NVARCHAR(MAX) = 'testTable', -- original table name HERE
#recordCount INT = 5, -- top number of records to insert to temp table
#buildStmt NVARCHAR(MAX),
#insertStmt NVARCHAR(MAX),
#valuesStmt NVARCHAR(MAX),
#insertCol NVARCHAR(MAX),
#strAgg NVARCHAR(MAX),
#insertOutput NVARCHAR(MAX)
IF (EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = #tableName))
BEGIN
-- build DROP and CREATE statements for temp table from original table
SET #buildStmt = 'IF OBJECT_ID(''tempdb..#' + #tableName + ''') IS NOT NULL DROP TABLE #' + #tableName + CHAR(10) + CHAR(10) +
'CREATE TABLE #' + #tableName + ' (' + CHAR(10)
SELECT #buildStmt = #buildStmt + ' ' + C.[Name] + ' ' +
T.[Name] +
CASE WHEN T.[Name] IN ('varchar','varchar','char','nchar') THEN '(' + CAST(C.[Length] AS VARCHAR) + ') ' ELSE ' ' END +
'NULL,' + CHAR(10)
FROM sysobjects O
JOIN syscolumns C ON C.id = O.id
JOIN systypes T ON T.xusertype = C.xusertype
WHERE O.[name] = #TableName
ORDER BY C.ColID
SET #buildStmt = SUBSTRING(#buildStmt,1,LEN(#buildStmt) - 2) + CHAR(10) + ')' + CHAR(10)
PRINT #buildStmt
-- build INSERT INTO statement from original table
SELECT #insertStmt = 'INSERT INTO #' + #tableName + ' (' +
STUFF ((
SELECT ', [' + C.[Name] + ']'
FROM sysobjects O
JOIN syscolumns C ON C.id = O.id
WHERE O.[name] = #TableName
ORDER BY C.ColID
FOR XML PATH('')), 1, 1, '')
+')'
PRINT #insertStmt
-- build VALUES portion of INSERT from data in original table
SELECT #insertCol = STUFF ((
SELECT '''''''''+CONVERT(NVARCHAR(200),' +
'[' + C.[Name] + ']' +
')+'''''',''+'
FROM sysobjects O
JOIN syscolumns C ON C.id = O.id
JOIN systypes T ON T.xusertype = C.xusertype
WHERE O.[name] = #TableName
ORDER BY C.ColID
FOR XML PATH('')), 1, 1, '')
SET #insertCol = SUBSTRING(#insertCol,1,LEN(#insertCol) - 1)
SELECT #strAgg = ';WITH CTE AS (SELECT TOP(' + CONVERT(VARCHAR,#recordCount) + ') * FROM ' + #tableName + ') ' +
' SELECT #valuesStmt = STRING_AGG(CAST(''' + #insertCol + ' AS NVARCHAR(MAX)),''), ('') ' +
' FROM CTE'
EXEC sp_executesql #strAgg,N'#valuesStmt NVARCHAR(MAX) OUTPUT', #valuesStmt OUTPUT
PRINT 'VALUES (' +REPLACE(SUBSTRING(#valuesStmt,1,LEN(#valuesStmt) - 1),',)',')') + ')'
END
ELSE
BEGIN
PRINT 'Table does NOT exist'
END