How to execute a stored procedure with parameters? - sql-server

Question

I have a database with 40 tables. I want to select data from a certain table by using a single stored procedure. First table (TblSPAU1) has 6 columns, named: ID, COL_SPAU1_EA, COL_SPAU1_EQ, COL_SPAU1_ore, COL_SPAU1_nivel, DateTime. Fourth table (TblSPAU4), for example, has this 6 columns: ID, COL_SPAU4_EA, COL_SPAU4_EQ, COL_SPAU4_ore, COL_SPAU4_nivel, DateTime. So what I want is to select data from table X from DateStart to DateStop. What I've done so far is:
USE [DBRapBreaza]
GO
/****** Object: StoredProcedure [dbo].[PS_SpauOPompa] Script Date: 12/19/2018 15:48:38 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[PS_SpauOPompa]
#DataStart datetime,
#DataStop datetime,
#val int
AS
BEGIN
SET NOCOUNT ON;
declare #sql NVARCHAR(max)
declare #col1 varchar
set #col1='ID'
declare #col2 varchar(25)
set #col2='COL_SPAU'+CONVERT(VARCHAR, #val)+'_EA'
declare #col3 varchar
set #col3='DateTime'
set #sql='select [ID]'+#col2+' FROM [DBRapBreaza].[dbo].[TblSPAU'+CONVERT(VARCHAR, #val)+ '] WHERE DateTime between'+CONVERT(VARCHAR(25), #DataStart,121)+ 'and'+CONVERT(VARCHAR(25), #DataStop,121)+';'
END
EXEC sp_sqlexec #sql, N'#DataStart datetime,#DataStop datetime,#val int', #DataStart, #DataStop, #val
I want to select, let's say, the ID and fist column from a certain table. #val represents the number of the table I want to select data from.
On sp_sqlexec I have a tool-tip which says that I have too many arguments specified. When I execute the EXEC, it throws me this error: Msg 137, Level 15, State 2, Line 1. Must declare the scalar variable "#sql".
My question is how should I execute this stored procedure?
Many thanks in advance!

Answer 1

First, you need some spaces in your string build. Specifically, change it to:
set #sql= 'select [ID], '+#col2+' FROM [DBRapBreaza].[dbo].[TblSPAU'+CONVERT(VARCHAR, #val)+ '] WHERE DateTime between '''+CONVERT(VARCHAR(25), #DataStart,121)+ ''' and '''+CONVERT(VARCHAR(25), #DataStop,121)+''';'
This will make your SQL look like this:
select [ID], COL_SPAU1_EA FROM [DBRapBreaza].[dbo].[TblSPAU1] WHERE DateTime between '2018-12-20 14:18:02.170' and '2018-12-20 14:18:02.170';
As opposed to the following:
select [ID]COL_SPAU1_EA FROM [DBRapBreaza].[dbo].[TblSPAU1] WHERE DateTime between2018-12-20 14:19:13.167and2018-12-20 14:19:13.167;
Which is missing:
A comma after the first column
Space between comma names (semantics)
Space after the word between
Quotes around the dates that will be evaluated from your parameters
Space before and after and in the where clause on your between statement
This is why it's always wise to use PRINT #sql while testing your dynamic SQL.
Then, once you move the END to the very bottom of the script, change your execution to:
EXEC sp_executesql
#sql,
N'#DataStart datetime, #DataStop datetime, #val int',
#DataStart, #DataStop, #val
This will leave you with the following code:
USE [DBRapBreaza]
GO
/****** Object: StoredProcedure [dbo].[PS_SpauOPompa] Script Date: 12/19/2018 15:48:38 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[PS_SpauOPompa]
#DataStart datetime,
#DataStop datetime,
#val int
AS
BEGIN
SET NOCOUNT ON;
declare #sql NVARCHAR(max)
declare #col1 varchar --missing a length here
declare #col2 varchar(25)
declare #col3 varchar --missing a length here
set #col1='ID'
set #col2='COL_SPAU'+CONVERT(VARCHAR, #val)+'_EA'
set #col3='DateTime'
set #sql= 'select [ID], '+#col2+' FROM [DBRapBreaza].[dbo].[TblSPAU'+CONVERT(VARCHAR, #val)+ '] WHERE DateTime between '''+CONVERT(VARCHAR(25), #DataStart,121)+ ''' and '''+CONVERT(VARCHAR(25), #DataStop,121)+''';'
--print #sql;
EXEC sp_executesql
#sql,
N'#DataStart datetime, #DataStop datetime, #val int',
#DataStart, #DataStop, #val;
END
Of note, you didn't specify a length for #col1 or #col3 which would default to 8 so be careful there. You never used this variable, so I'm not sure what it's purpose is.