Select into tables dynamically with variables - sql

Question

I have some code to create tables based on a set of dates I define.
Example, I have 5 dates, and they are aren't consecutive. For any of these dates, I want to create a table and I am currently using a Select into.
I am having to do this 5 times, even though the only thing changing is the name of the new table created and the date. Is there a way to do this in an elegant way.
I started writing some code, but I am struggling to get it to loop through all the dates I want. The way I have written it currently, I only works if I edit the date at the start.
DECLARE #MyDate DATE;
SET #MyDate = '2019-01-01';
SET #TableName = 'Table1';
SELECT *
into #TableName
FROM Original_Table
WHERE Query_Date = #MyDate;

Answer 1

Is this a one time thing or do you have to do this on a regular basis?
If it's the first, than I would just do it and get it over with.
If it's the latter, then I suspect something is very wrong with the way that system is designed - but assuming that can't be changed, you can create a stored procedure that will do this using dynamic SQL.
Something like this can get you started:
CREATE PROCEDURE dbo.CreateTableBasedOnDate
(
#MyDate DATE,
-- sysname is a system data type for identifiers: a non-nullable nvarchar(128).
#TableName sysname
)
AS
-- 200 is long enough. Yes, I did the math.
DECLARE #Sql nvarchar(200) =
-- Note: I'm not convinced that quotename is enough to protect you from sql injection.
-- you should be very careful with what user is allowed to execute this procedure.
N'SELECT * into '+ QUOTENAME(#TableName) +N'
FROM Original_Table
WHERE Query_Date = #MyDate;';
-- When dealing with dynamic SQL, Print is your best friend.
-- Remark this row and unremark the next only once you've verified you get the correct SQL
PRINT #SQL;
--EXEC sp_ExecuteSql #Sql, N'#MyDate Date', #MyDate
GO
Usage:
EXEC CreateTableBasedOnDate '2018-01-01', 'zohar';

Answer 2

Use dynamic SQL:
DECLARE #MyDate DATE, #TableName varchar(50);
SET #MyDate = '2019-01-01';
SET #TableName = 'Table1';
DECLARE #sql NVARCHAR(4000);
DECLARE #params NVARCHAR(4000);
SELECT #sql=N'
SELECT *
INTO ' + QUOTENAME(#TableName) + '
FROM Original_Table
WHERE Query_Date = #MyDate;';
SELECT #params = N'#MyDate DATE';
EXEC sys.sp_executesql #sql, #params, #MyDate=#MyDate
Note that dynamic SQL can be dangerous as it opens up a path for SQL injection. Its fine if you are just using it in your own local scripts, but take care if you e.g. wrap this in a procedure that is more widely accessible.

Answer 3

I would use dynamic SQL although I would add another variables for the schema:
DECLARE
#MyDate nVarchar(50) = '2019-01-01',
#Schema nVarchar (50) = 'dbo',
#TableName nVarchar(250) = 'Table1',
#SQL nVarchar(500);
Set #SQL = '
SELECT *
into '+ QUOTENAME(#Schema)+'.'+ QUOTENAME(#TableName) +'
FROM Original_Table
WHERE Query_Date = '+ #MyDate +';
'
--print #SQL
Exec(#SQL)
You can use the print statement to see how the SQL will look before executing this properly. You may also want to look at adding this as a stored procedure.