Loop over SQL commands in a file - sql

Question

I have an SQL file that looks like this (clearly the real thing is a bit longer and actualy does stuff :))
DECLARE #Mandatory int = 0
DECLARE #Fish int = 3
DECLARE #InitialPriceID int
if #Mandatory= 0
begin
select #InitialPriceID = priceID from Fishes where FishID = #Fish
end
I have a file of 'Mandatory' and 'Fish' values
Mandatory,Fish
1,3
0,4
1,4
1,3
1,7
I need to write a program that will produce an SQL file (or files) for our DBO to run against the database. but I am not quite sure how to approach the problem...
Cheers

Answer 1

You should generally prefer set based solutions. I've no idea what the full solution would look like, but from the start you've given:
declare #Values table (Mandatory int,Fish int)
insert into #Values(Mandatory,Fish) values
(1,3),
(0,4),
(1,4),
(1,3),
(1,7),
;with Prices as (
select
Mandatory,
Fish,
CASE
WHEN Mandatory = 0 THEN f.PriceID
ELSE 55 /* Calculation for Mandatory = 1? */
END as InitialPriceID
from
#Values v
left join /* Or inner join? */
Fishes f
on
v.Fish = f.Fish
) select * from Prices
You should aim to compute all of the results in one go, rather than trying to "loop through" each calculation. SQL works better this way.

Answer 2

At the risk of over-simplifying things in C# or similar you could use a string processing approach:
class Program
{
static void Main(string[] args)
{
var sb = new StringBuilder();
foreach(var line in File.ReadLines(#"c:\myfile.csv"))
{
string[] values = line.Split(',');
int mandatory = Int32.Parse(values[0]);
int fish = Int32.Parse(values[1]);
sb.AppendLine(new Foo(mandatory, fish).ToString());
}
File.WriteAllText("#c:\myfile.sql", sb.ToString());
}
private sealed class Foo
{
public Foo(int mandatory, int fish)
{
this.Mandatory = mandatory;
this.Fish = fish;
}
public int Mandatory { get; private set; }
public int Fish { get; set; }
public override string ToString()
{
return String.Format(#"DECLARE #Mandatory int = {0}
DECLARE #Fish int = {1}
DECLARE #InitialPriceID int
if #Mandatory=
begin
select #InitialPriceID = priceID from Fishes where FishID = #Fish
end
", this.Mandatory, this.Fish);
}
}
}

Answer 3

There are many article on how to read from a text file through t-sql, check "Stored Procedure to Open and Read a text file" on SO and if you can make change the format of you input files into xml, then you can check SQL SERVER – Simple Example of Reading XML File Using T-SQL