Dynamically created Tables JOIN in SQL Server - sql

Question

I have 3 types of tables
Major table as follows
CREATE TABLE #InitialTable
(
Id int PRIMARY KEY IDENTITY(1,1),
RP varchar(20)
)
INSERT INTO #InitialTable
VALUES ('R1', 'R2', 'R3')
GO
Table contains dynamically created tables information as follows
CREATE TABLE #DynamicTablesInfo
(
Id int PRIMARY KEY IDENTITY(1,1),
RPId int FOREIGN KEY REFERENCES #InitialTable(Id),
TableName varchar(100)
)
GO
INSERT INTO #DynamicTablesInfo
VALUES (1, 'Table_X1'), (2, 'Table_X2'), (3, 'Table_X3')
GO
Dynamically created tables these tables can be any number of tables and the tables info is available in above table.
CREATE TABLE #Table_X1
(
Id int PRIMARY KEY IDENTITY,
Version_Value varchar(100)
)
GO
INSERT INTO #Table_X1
VALUES ('Val_X1_1'), ('Val_X1_2'), ('Val_X1_3')
GO
CREATE TABLE #Table_X2
(
Id int PRIMARY KEY IDENTITY,
Version_Value varchar(100)
)
GO
INSERT INTO #Table_X2
VALUES ('Val_X2_1'), ('Val_X2_2'), ('Val_X2_3')
GO
CREATE TABLE #Table_X3
(
Id int PRIMARY KEY IDENTITY,
Version_Value varchar(100)
)
GO
INSERT INTO #Table_X3
VALUES ('Val_X3_1'), ('Val_X3_2'), ('Val_X3_3')
GO
Now I wanted to join InitialTable with dynamically created tables (Table_X1, Table_X2, Table_X3,....) with the help of DynamicTablesInfo table - how to do that?
Note: for easy update, delete, insert I created them as temporary tables but in my application all are real tables.

Answer 1

Instead of doing this:
CREATE TABLE #Table_X1
(
Id int PRIMARY KEY IDENTITY
,Version_Value varchar(100)
)
GO
CREATE TABLE #Table_X2
(
Id int PRIMARY KEY IDENTITY
,Version_Value varchar(100)
)
GO
CREATE TABLE #Table_X3
(
Id int PRIMARY KEY IDENTITY
,Version_Value varchar(100)
)
GO
Do this one time:
CREATE TABLE Table_X
(
Id int PRIMARY KEY IDENTITY
,Version_Value varchar(100)
,X_number INT
)
GO
Then instead of doing this:
INSERT INTO #Table_X1 VALUES ('Val_X1_1'),('Val_X1_2'),('Val_X1_3')
INSERT INTO #Table_X2 VALUES ('Val_X2_1'),('Val_X2_2'),('Val_X2_3')
INSERT INTO #Table_X3 VALUES ('Val_X3_1'),('Val_X3_2'),('Val_X3_3')
Do this:
INSERT INTO Table_X VALUES ('Val_X1_1',1),('Val_X1_2',1),('Val_X1_3',1)
INSERT INTO Table_X VALUES ('Val_X2_1',2),('Val_X2_2',2),('Val_X2_3',2)
INSERT INTO Table_X VALUES ('Val_X3_1',3),('Val_X3_2',3),('Val_X3_3',3)
Much easier to query without dynamics:
--no
SELECT * FROM Table_X1
--yes
SELECY * FROM Table_X WHERE X_Number = 1
You've indicated you're stuck with it how it is, so you'll need to create and run your queries dynamically too. This is c#/vb flavored pseudocode:
string sql = "SELECT * FROM sometable"
for int x = 1 to 3
sql = sql + " table_x{x} on sometable.id = table_x{x}.id"
Or perhaps build a Union:
string sql = "WITH allx AS (SELECT * FROM table_x1"
for int x = 2 to 10
sql = sql + " UNION ALL SELECT * FROM table_x{x}"
sql = sql + ") select * from sometable inner join allx on..."
But I echo larnu's sentiments in the comments.. if you truly cannot change the tables that are created, consider creating a VIEW in a similar way to the UNION code above, that will sit alongside X number of tables and will provide a way to query without dynamic:
CREATE VIEW AllX AS(
SELECT x.*, 1 as Which FROM TABLE_X1 x
UNION ALL SELECT x.*, 2 as Which FROM TABLE_X2 x
UNION ALL SELECT x.*, 3 as Which FROM TABLE_X3 x
...
Use the same technique that creates 10 tables to string together a CREATE VIEW statement that views over the 10 tables, then you can query the view without Dynamic sql generation