Loop through each table in database and get first three digits of one column - tsql

Question

I am trying to create a table that will show me each table name, and the first three characters of the ID column (every table has this column), and then put that data into a table. We are using this to help map dependencies in our Salesforce Org which is replicated onto SQL using dbAMP. I adapted the code below as far as I could, and am looking for help to finish it.
UPDATE: The first half of the question is resolved, and the code now runs to give the first three characters of the ID. I still could use help in converting this code to spool the results into one single table.
USE Salesforce
GO
IF OBJECT_ID('tempdb..#tempResults') IS NOT NULL
DROP TABLE #tempResults
CREATE TABLE #tempResults
(
[Object_ID] VARCHAR(3)
--, [org] VARCHAR(100)
, [Table_Name] VARCHAR(100)
)
DECLARE cur CURSOR FOR
SELECT
'SELECT DISTINCT LEFT(' + QUOTENAME(c.COLUMN_NAME) + ',3) AS
[Object_ID], '''
--+ QUOTENAME(TABLE_CATALOG) + ' as [Org], '
+ QUOTENAME(TABLE_NAME) + ''' as [Table_Name] FROM '
+ QUOTENAME(TABLE_CATALOG) + '.' + QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME)
FROM INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.[DATA_TYPE] IN ('nchar','varchar', 'nvarchar')
AND c.[CHARACTER_MAXIMUM_LENGTH] = 18
and c.TABLE_NAME not like '%upload%'
and c.TABLE_NAME not like '%Delta%'
and c.TABLE_NAME not like '%Update%'
and c.TABLE_NAME not like '%Previous%'
and C.COLUMN_NAME = 'ID'
DECLARE #cmd VARCHAR(MAX);
OPEN cur;
FETCH NEXT FROM cur INTO #cmd;
WHILE ##FETCH_STATUS = 0
BEGIN
--PRINT #cmd
INSERT INTO #tempResults
EXEC(#cmd);
FETCH NEXT FROM cur INTO #cmd;
END
CLOSE cur;
DEALLOCATE cur;
SELECT * FROM #tempResults
I'm not getting the Column ID trimmed to the first 3 characters, and it's not outputting to a table. I'm not that familiar with cursors so I'd appreciate any help. Thanks,

Answer 1

You're really close. The way you've got your select written it's actually trimming the column name and then appending that 3-character column name to the string, rather than getting the first three characters from the actual data within the ID column.
Try updating your select so the LEFT brackets the QUOTENAME(c.COLUMN_NAME) inside the string, like below. This small change made your script work on my salesforce installation.
SELECT
'SELECT DISTINCT LEFT(' + QUOTENAME(c.COLUMN_NAME) + ',3) AS '
+ QUOTENAME(TABLE_CATALOG + '.' + TABLE_SCHEMA + '.' + TABLE_NAME) + ' FROM '
+ QUOTENAME(TABLE_CATALOG) + '.' + QUOTENAME(TABLE_SCHEMA) + '.'
+ QUOTENAME(TABLE_NAME)
FROM INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.[DATA_TYPE] IN ('nchar','varchar', 'nvarchar')
AND c.[CHARACTER_MAXIMUM_LENGTH] = 18
and c.TABLE_NAME not like '%upload%'
and c.TABLE_NAME not like '%Delta%'
and c.TABLE_NAME not like '%UPdate%'
and c.TABLE_NAME not like '%Previous%'
and C.COLUMN_NAME = 'ID'
Update to answer part two:
First you'll need a destination table - I've used a temporary table, but this will work just fine as a permanent table.
I've adjusted the code to output two columns instead of one: IDSubstring (your 3-character ID portion) and SourceTable (this is exactly the same information that you were using as a column name previously). This way we know which table the ID portion belongs to.
Then, inside the cursor, instead of just executing, we do this:
INSERT INTO #tempResults
EXEC(#cmd);
This will populate our table and give us selectable values.
CREATE TABLE #tempResults
(
[IDSubstring] VARCHAR(3)
, [SourceTable] VARCHAR(50)
)
DECLARE cur CURSOR FOR
SELECT
'SELECT DISTINCT LEFT(' + QUOTENAME(c.COLUMN_NAME) + ',3) AS [IDSubstring], '''
+ QUOTENAME(TABLE_CATALOG + '.' + TABLE_SCHEMA + '.' + TABLE_NAME) + ''' as [SourceTable] FROM '
+ QUOTENAME(TABLE_CATALOG) + '.' + QUOTENAME(TABLE_SCHEMA) + '.'
+ QUOTENAME(TABLE_NAME)
FROM INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.[DATA_TYPE] IN ('nchar','varchar', 'nvarchar')
AND c.[CHARACTER_MAXIMUM_LENGTH] = 18
and c.TABLE_NAME not like '%upload%'
and c.TABLE_NAME not like '%Delta%'
and c.TABLE_NAME not like '%UPdate%'
and c.TABLE_NAME not like '%Previous%'
and C.COLUMN_NAME = 'ID'
DECLARE #cmd VARCHAR(MAX);
OPEN cur;
FETCH NEXT FROM cur INTO #cmd;
WHILE ##FETCH_STATUS = 0
BEGIN
--PRINT #cmd
INSERT INTO #tempResults
EXEC(#cmd);
FETCH NEXT FROM cur INTO #cmd;
END
CLOSE cur;
DEALLOCATE cur;
SELECT * FROM #tempResults
Update 2
You're correct in assuming it's an issue with the '''
The ''' is there because we need to build our string with single quotes inside of it.
As examples:
SELECT '' returns nothing
while SELECT '''' returns '
And SELECT 'This is an example''' will return This is an example'
So the ''' are part of a larger string definition started with the initial ' before "This" and can be broken down this way - the first two single quotes are the single quote we want to print within the string and the third single quote is the string terminating quote. If you just run the select statement and look at what it outputs, you can see where each single quote has been inserted into the string.
Updated SELECT is below.
SELECT
'SELECT DISTINCT LEFT(' + QUOTENAME(c.COLUMN_NAME) + ',3) AS [Object_ID], '''
+ QUOTENAME(TABLE_CATALOG) + ''' as [Org], '''
+ QUOTENAME(TABLE_NAME) + ''' as [Table_Name] FROM '
+ QUOTENAME(TABLE_CATALOG) + '.' + QUOTENAME(TABLE_SCHEMA) + '.' + QUOTENAME(TABLE_NAME)
FROM INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.[DATA_TYPE] IN ('nchar','varchar', 'nvarchar')
AND c.[CHARACTER_MAXIMUM_LENGTH] = 18
and c.TABLE_NAME not like '%upload%'
and c.TABLE_NAME not like '%Delta%'
and c.TABLE_NAME not like '%Update%'
and c.TABLE_NAME not like '%Previous%'
and C.COLUMN_NAME = 'ID'