SQL: How to refer to a dynamic column name to make calculation - sql-server

I'd like to update fields while referring to a dynamic column.
The goal is to automate a process because each month the column to refer to changes.
For example it's like having different columns like month1, month2, month3 until month24. Each month, only 1 column needs to be updated but it's a running number that is calculated in another table.
So my question is how to make the query dynamic so that every month i only update the column number that i want and not the other one.
I tried the script below but the following issue comes up
Error converting data type varchar to float.
DECLARE #PromoMonthNumber VARCHAR(60)
DECLARE #PromoMonth VARCHAR(600)
SET #PromoMonthNumber = (SELECT CurrentDemandIndex FROM RidgeSys) --This refer to a number that change all the time
SET #PromoMonth = 'SELECT ABC.PromotionHistory' + #PromoMonthNumber
UPDATE ABC
SET #PromoMonth = table2.promotionhistory
FROM ABC
INNER JOIN (
SELECT Article.code as code, sum(ROUND(#PromoMonth,0)) as promotionhistory
FROM Article
INNER JOIN ABC ON DEF.articlecode = ABC.Articlecode
) as table2
ON ABC.articlecode = table2.code)

Here is your issue:
SELECT Article.code as code, sum(ROUND(#PromoMonth,0)) as promotionhistory
Since #PromoMonth is defined as VARCHAR, if the value is non-numeric, it will fail. Here is an example:
This works fine:
declare #x varchar(100) = '1';
select sum(round(#x,0));
Result:
1
This fails with same error above:
declare #x varchar(100) = 'x';
select sum(round(#x,0));
Result:
Msg 8114, Level 16, State 5, Line 3
Error converting data type varchar to float.
You need to check that the value is numeric before you do the calculation.

Related

Conversion of scalar variable in query

I am working with public database Wide World Importers and I try to make some query.For input in this query I want to use scalar variables. You can see code below:
DECLARE #SupplierID int = 7
DECLARE #YearMonth NVARCHAR = '2013.1'
SELECT
pur.SupplierID, SUM(purst.TransactionAmount) AS TotalTransaction,
CONCAT(YEAR(pur.OrderDate), '.', MONTH(pur.OrderDate)) AS YearMonth
FROM
[Purchasing].[PurchaseOrders] AS pur
INNER JOIN
[Purchasing].[SupplierTransactions] AS purst ON purst.SupplierID = pur.SupplierID
WHERE
pur.SupplierID = #SupplierID
AND YearMonth = #YearMonth
GROUP BY
pur.OrderDate, pur.SupplierID
Above code work well and give me good result (but without scalar variable #YearMonth). You can see result below:
But when I try to include YearMonth like scalar variable into this query I get this error:
Msg 207, Level 16, State 1, Line 3831
Invalid column name 'YearMonth'
So can anybody help me how to fix this problem and make query properly?
You can't reference a column declared in the SELECT in the WHERE. You need to reference the actual columns in the table in the WHERE, or use a subquery or CTE.
What you should be doing here, however, is using proper date logic:
DECLARE #SupplierID int = 7,
#StartDate date = '20130101',
#EndDate date = '20130201';
SELECT PO.SupplierID,
SUM(ST.TransactionAmount) AS TotalTransaction,
CONCAT(YEAR(PO.OrderDate), '.', MONTH(PO.OrderDate)) AS YearMonth
FROM [Purchasing].[PurchaseOrders] PO
INNER JOIN [Purchasing].[SupplierTransactions] ST ON ST.SupplierID = PO.SupplierID
WHERE PO.SupplierID = #SupplierID
AND PO.OrderDate >= #StartDate
AND PO.OrderDate < #EndDate
GROUP BY PO.OrderDate,
PO.SupplierID;
I also change your aliases to something a bit more appropriate.

How to loop with different values in T-SQL query?

I have some specific set of values that I want to filter on a column, I don't want to do an 'in' clause in SQL Server. I want to use loop to pass in different set of values each time.
For example if there is a name column in my data, and I want to run query 5 times with different filter value.
Please look at the loop query attached below.
DECLARE #cnt INT = 1;
WHILE #cnt < 94
BEGIN
SELECT Name, COUNT(*) AS Number_of_Names
FROM Table
WHERE name IN ('John')
AND value IS NOT NULL
GROUP BY Name
SET #cnt = #cnt + 1;
END;
I want to pass in different values under 'name' column at each loop like john in the case above, then mary in the next loop likewise based on set of values I pass in the variable like #values = John,Mary,Nicole,matt etc..
Considering the comments on your question, this should give you an idea on how to achieve a solution without using loops and still get all the names even when the name is not present on the table.
SELECT Name,
COUNT(value) AS Number_of_Names --Only count when value is not null
FROM (VALUES('John'), ('Mary'), ('Nicole'), ('Matt'))Names(name) --This can be replaced by a table-valued parameter or temp table.
LEFT JOIN Table t ON Names.name = t.name
--WHERE name IN ('John') /*No longer needed*/
--AND value IS NOT NULL /*Removed this because it would make the OUTER JOIN behave as an INNER JOIN*/
GROUP BY Name;

How do SQL Server variables work?

I have a table with salary of multiple employees.
I need to calculate score for these employees using a derived number (mean and stddev) and include it as a new column.
I know I can do this in the select statement, but if I wanted see if I can use variables.
So that changes can be made dynamically. I am new to SQL and just trying to learn things here.
declare #Weight int,
#weight2 int,
#Mean int,
#StdDevn int,
#Variance int
set #Weight = 30
set #weight2 = (POWER(#weight,2)/100)
SELECT #Mean = AVG(salary) FROM [live].[dbo].[salary]
SELECT #StdDevn = STDEV(salary) FROM [live].[dbo].[salary]
SELECT #Variance = (POWER(#StdDevn,2)/100)
-- I should include some code here so that the above variable are passed to below query
SELECT * FROM [live].[dbo].[salary], (([salary]-#Mean)/#StdDevn)
Error:
Must declare variable #Mean, Incorrect syntax near '-'.
The problem you have is how you are trying to select.
The variable #Mean is declared and it would work if the final select would be something like below:
SELECT *,
(([salary]-#Mean)/#StdDevn) as SomeOtherCol
FROM [live].[dbo].[salary]
The SomeOtherCol will be then shown as the last column of your result set.

Drop table in Stored Procedure not working properly?

I have a stored procedure which drops a table if it exists, then it re-creates the table & fills it with relevant data, a friend of mine has about the same code, the only real difference is in the column headers for the table.
As an illustration, here's how mine looks (not really, just a representation).
+----+-----+-----+--------+
| ID | Foo | Bar | Number |
+----+-----+-----+--------+
| 1 | x | x | 0 |
| 2 | x | x | 1 |
+----+-----+-----+--------+
And here's what his might look like
+----+--------+--------+-----+--------+
| ID | BarFoo | FooBar | Num | Suffix |
+----+--------+--------+-----+--------+
| 1 | x | x | 0 | a |
| 2 | x | x | 1 | b |
+----+--------+--------+-----+--------+
Again, these are merely representations of the situation.
As this is to be a school assignment, the teacher will be creating & executing both SP's, however when creating the SP after using another, I get this error:
Msg 207, Level 16, State 1, Procedure XYZ, Line 59
Invalid column name 'Foo'.
Msg 213, Level 16, State 1, Procedure XYZ, Line 61
Column name or number of supplied values does not match table definition.
However, at the start of both stored procedures, we have this:
CREATE PROCEDURE XYZ
AS
BEGIN
IF EXISTS (SELECT name
FROM sysobjects
WHERE name = 'TABLENAME'
AND xtype = 'u')
DROP TABLE TABLENAME;
From what I understand, this should remove the entire table? Including table/column definitions & data?
The only fix I've found so far, is to either execute the DROP TABLE separately before creating the stored procedure, which won't work for us as it really has to be within the stored procedure.
Help would be much appreciated :)
EDIT: Here's my ACTUAL code, apart from comments, this is exactly how it looks in my script (excluding other code behind it).
IF EXISTS (SELECT name
FROM sysobjects
WHERE name = 'BerekenStatistiek'
AND xtype = 'p')
DROP PROCEDURE BerekenStatistiek;
GO
CREATE PROCEDURE BerekenStatistiek
#jaar INT=0
AS
BEGIN
IF EXISTS (SELECT name
FROM sysobjects
WHERE name = 'Statistiek'
AND xtype = 'u')
DROP TABLE Statistiek;
DECLARE #year AS NVARCHAR (4);
SET #year = CONVERT (NVARCHAR (4), #jaar);
SELECT *,
CAST (Kost - Korting + Freight AS MONEY) AS Netto,
'' AS Richting
INTO Statistiek
FROM (SELECT O.Kwartaal,
CAST (SUM(O.Kost) AS MONEY) AS Kost,
CAST (SUM(O.Korting) AS MONEY) AS Korting,
CAST (SUM(O.Freight) AS MONEY) AS Freight
FROM (SELECT CASE
WHEN CONVERT (NVARCHAR (8), OrderDate, 112) BETWEEN #year + '0101' AND #year + '0331' THEN 1
WHEN CONVERT (NVARCHAR (8), OrderDate, 112) BETWEEN #year + '0401' AND #year + '0630' THEN 2
WHEN CONVERT (NVARCHAR (8), OrderDate, 112) BETWEEN #year + '0701' AND #year + '0930' THEN 3
WHEN CONVERT (NVARCHAR (8), OrderDate, 112) BETWEEN #year + '1001' AND #year + '1231' THEN 4
END AS 'Kwartaal',
ROUND(UnitPrice * Quantity, 2) AS Kost,
Round((UnitPrice * Quantity) * Discount, 2) AS Korting,
Freight
FROM Orders AS O
INNER JOIN
OrderDetails AS Od
ON O.OrderID = Od.OrderID
WHERE CONVERT (NVARCHAR (4), OrderDate, 112) = #year) AS O
GROUP BY O.Kwartaal) AS O1;
ALTER TABLE Statistiek ALTER COLUMN Kwartaal INT NOT NULL;
ALTER TABLE Statistiek ALTER COLUMN Richting NVARCHAR (8);
ALTER TABLE Statistiek
ADD PRIMARY KEY (Kwartaal);
...
And here's his code (the insertion of values in the variables are excluded just for readability (his code is a bit more bulky):
IF EXISTS (SELECT name
FROM sysobjects
WHERE name = 'BerekenStatistiek'
AND xtype = 'p')
BEGIN
DROP PROCEDURE BerekenStatistiek;
END
GO
CREATE PROCEDURE BerekenStatistiek
#jaartal INT
AS
BEGIN
DECLARE #huidigkwartaal AS INT = 1;
DECLARE #beginmaand AS INT;
DECLARE #eindmaand AS INT;
DECLARE #vorige_netto_ontvangsten AS MONEY;
IF EXISTS (SELECT *
FROM sysobjects
WHERE name = 'Statistiek'
AND xtype = 'U')
BEGIN
DROP TABLE Statistiek;
END
CREATE TABLE Statistiek
(
kwartaalnummer INT ,
beginmaand INT ,
eindmaand INT ,
orderbedrag MONEY ,
korting MONEY ,
vervoerskost MONEY ,
netto_ontvangsten MONEY ,
stijgend_dalend_gelijk NVARCHAR (10)
);
--Variables get their data here.
INSERT INTO Statistiek (kwartaalnummer, beginmaand, eindmaand, orderbedrag, korting, vervoerskost, netto_ontvangsten, stijgend_dalend_gelijk)
VALUES (#huidigkwartaal, #beginmaand, #eindmaand, #orderbedrag, #korting, #vervoerskost, #netto_ontvangsten, #stijgend_dalend_gelijk);
"however when creating the SP after using another, I get this error" (Emphasis added.)
SQL Server will insist that a stored procedure match the definitions of tables that exist as the time the stored procedure is created. If the table does not exist when the stored procedure is created, SQL Server will assume that a matching table will appear at run time.
create table t (c int)
go
create procedure p as begin
drop table t
select 1 as diff_column_name into t
select diff_colun_name from t
end
results in:
Msg 207, Level 16, State 1, Procedure p, Line 6
Invalid column name 'diff_colun_name'.
Now, drop table t, and the procedure cane be created:
drop table t
go
create procedure p as begin
drop table t
select 1 as diff_column_name into t
select diff_colun_name from t
end
Command(s) completed successfully.
If you can use a different table name, start with that. And, if the table has to exist only for a moment after the proc is executed so that it can be selected from, then create a global temporary table (i.e. table name starts with ## as in ##MyTable).
However, if it is a requirement to use the same table name as your classmate, then the teacher is probably trying to get you to learn about deferred object resolution (i.e. #Shannon's answer) and how to get around it, because outside of learning this, the scenario makes no sense since one would never do such a thing in reality.
Sub-processes (i.e. EXEC and sp_executesql) do not resolve immediately since they aren't executed when creating the stored procedure. So, simplistically, just declare a new NVARCHAR(MAX) variable to hold some Dynamic SQL and put your SELECT statement in there. Use sp_executesql to pass in the #year variable. You are creating a real table so it will survive beyond the subprocess ending and then the ALTER TABLE statement will work.
Additional notes:
You don't really need the ALTER statement to set the datatype of the [Richting] field. Just tell SQL Server what the type is in your SELECT statement:
CONVERT(NVARCHAR(8), '') AS [Richting]
You don't really want to do CONVERT(NVARCHAR(8), OrderDate, 112) to compare to a value as it invalidates the use of any indexes that might be on [OrderDate]. Instead, construct a date value from the strings and convert that to a DATETIME or DATE (i.e. CONVERT(DATETIME, #year + '0101')).
To better understand this issue, please read Sargability: Why %string% Is Slow, and at least the first link at the bottom, which is: What makes a SQL statement sargable?
You don't really want to convert the OrderDate field to NVARCHAR(4) just to compare the year, for the same reason as just mentioned in the above point. At the very least using the YEAR() function would be more direct. But if you want to make sure indexes can be used, you can't put a function on the field. But you only want the year. So isn't the year the same as BETWEEN #Year + '0101' AND #Year + '1231'? ;-)
Interestingly enough, the first example in the accepted answer in the "What makes a SQL statement sargable?" S.O. question linked in the previous bullet is exactly what I am recommending here :).
For I can understand, the wrong queries are the inserts, because the engine can't find correct table structure, check if the inserts have the same structure of your second table example. Dont forget to check the USE at the beginning of the script, maybe you are using a different db, this can happen :).
In the last bit of code, you are having
AND xtype = 'U'
If your collation is case sensitive, the drop is not taking place and thus the error.

Error converting data type varchar to numeric. SQL Server

I'm writing data on the Sql Server database.
When data is written, a trigger runs.
TRIGGER
ALTER TRIGGER Alert ON records AFTER INSERT AS
BEGIN
DECLARE #tempmin decimal = 0
DECLARE #current_max_idAlarm int = (SELECT MAX(IdAlarm) FROM alarms)
DECLARE #maxidAlarm int
DECLARE #temp decimal = (SELECT s.lim_inf_temp from sensores s JOIN inserted i ON s.idSensor=i.idSensor )
-- Insert into alares from the inserted rows if temperature less than tempmin
SET IDENTITY_INSERT alarmes On
INSERT alarmes (IdAlarm, desc_alarm,date, idRecord)
SELECT
ROW_NUMBER() OVER (ORDER BY i.idRecord) + #current_max_idAlarm, 'Temp Error', GETDATE(), i.idRecord
FROM
inserted AS i
WHERE
i.Temperature < #temp
end
INSERT
insert into record values ('2014-05-26' ,'14:51:47','Sensor01','---','48.6','9.8');
Whenever I try to record this type of data: '---'
Gives the following error:
Msg 8114, Level 16, State 5, Procedure Alert, Line
Error converting data type varchar to numeric.
I know it is to be in decimal type (DECLARE #temp decimal - TRIGGER), but moving to the type varchar to trigger stops working correctly.
Does someone can help me resolve this error please?
Thank you all.
You are trying to insert --- inside a numeric column, you simply can't do that.
You have mainly 2 options:
Change the data type of the destination column
Choose a different value to insert (like NULL)

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