Sql Server how to find values in different tables that have different suffix - sql

Question

I'm struggling to find a value that might be in different tables but using UNION is a pain as there are a lot of tables.
[Different table that contains the suffixes from the TestTable_]
| ID | Name|
| -------- | -----------|
| 1 | TestTable1 |
| 2 | TestTable2 |
| 3 | TestTable3 |
| 4 | TestTable4 |
TestTable1 content:
| id | Name | q1 | a1 |
| -------- | ---------------------------------------- |
| 1 | goose | withFeather? |featherID |
| 2 | rooster| withoutFeather?|shinyfeatherID |
| 3 | rooster| age | 20 |
TestTable2 content:
| id | Name | q1 | a1 |
| -------- | ---------------------------------------------------|
| 1 | brazilian_goose | withFeather? |featherID |
| 2 | annoying_rooster | withoutFeather?|shinyfeatherID |
| 3 | annoying_rooster | no_legs? |dead |
TestTable3 content:
| id | Name | q1 | a1 |
| -------- | ---------------------------------------- |
| 1 | goose | withFeather? |featherID |
| 2 | rooster| withoutFeather?|shinyfeatherID |
| 3 | rooster| age | 15 |
Common columns: q1 and a1
Is there a way to parse through all of them to lookup for a specific value without using UNION because some of them might have different columns?
Something like: check if "q1='age'" exists in all those tables (from 1 to 50)
Select q1,*
from (something)
where q1 exists in (TestTable_*)... or something like that.
If not possible, not a problem.

Answer 1

You could use dynamic SQL but something I do in situations like this where I have a list of tables that I want to quickly perform the same actions on is to either use a spreadsheet to paste the list of tables into and type a query into the cell with something like #table then use the substitute function to replace it.
Alternative I just paste the list into SSMS and use SHIFT+ALT+ArrowKey to select the column and start typing stuff out.
So here is my list of tables
Then I use that key combo. As you can see my cursor has now selected all those rows.
Now I can start typing and all rows selected will get the input.
Then I just go to the other side of the table names and repeat the action
It's not a perfect solution but it's quick a quick and dirty way of doing something repetitive quickly.
If you want to find all the tables with that column name you can use information schema.
Select table_name from INFORMATION_SCHEMA.COLUMNS where COLUMN_NAME = 'q1'

Answer 2

Given the type of solution you are after I can offer a method that I've had to use on legacy systems.
You can query sys.columns for the name of the column(s) you need to find in N tables and join using object_id to sys.tables where type='U'. This will give you a list of table names.
From this list you can then build a working query for each table, and depending on your requirements (is this ad-hoc?) either just manually execute it yourself of build a procedure that will do it for you using sp_executesql
Eg
select t.name, c.name
into #workingtable
from sys.columns c
join sys.tables t on t.object_id=c.object_id
where c.name in .....
psudocode:
begin loop while rows exist in #working table
select top 1 row from #workingtable
set #sql=your query specific to that table and column(s)
exec(#sql) / sp_executesql / try/catch as necessary
delete row from working table
end loop
Hopefully that give ideas at least for how you might implement your requirements.