I am trying to achieve something along the lines of a for-each, where I would like to take the Ids of a returned select statement and use each of them.
DECLARE @i int
DECLARE @PractitionerId int
DECLARE @numrows int
DECLARE @Practitioner TABLE (
idx smallint Primary Key IDENTITY(1,1)
, PractitionerId int
)
INSERT @Practitioner
SELECT distinct PractitionerId FROM Practitioner
SET @i = 1
SET @numrows = (SELECT COUNT(*) FROM Practitioner)
IF @numrows > 0
WHILE (@i <= (SELECT MAX(idx) FROM Practitioner))
BEGIN
SET @PractitionerId = (SELECT PractitionerId FROM @Practitioner WHERE idx = @i)
--Do something with Id here
PRINT @PractitionerId
SET @i = @i + 1
END
At the moment I have something that looks like the above, but am getting the error:
Invalid column name 'idx'.
This question is related to
sql-server
tsql
I came up with a very effective, (I think) readable way to do this.
1. create a temp table and put the records you want to iterate in there
2. use WHILE @@ROWCOUNT <> 0 to do the iterating
3. to get one row at a time do, SELECT TOP 1 <fieldnames>
b. save the unique ID for that row in a variable
4. Do Stuff, then delete the row from the temp table based on the ID saved at step 3b.
Here's the code. Sorry, its using my variable names instead of the ones in the question.
declare @tempPFRunStops TABLE (ProformaRunStopsID int,ProformaRunMasterID int, CompanyLocationID int, StopSequence int );
INSERT @tempPFRunStops (ProformaRunStopsID,ProformaRunMasterID, CompanyLocationID, StopSequence)
SELECT ProformaRunStopsID, ProformaRunMasterID, CompanyLocationID, StopSequence from ProformaRunStops
WHERE ProformaRunMasterID IN ( SELECT ProformaRunMasterID FROM ProformaRunMaster WHERE ProformaId = 15 )
-- SELECT * FROM @tempPFRunStops
WHILE @@ROWCOUNT <> 0 -- << I dont know how this works
BEGIN
SELECT TOP 1 * FROM @tempPFRunStops
-- I could have put the unique ID into a variable here
SELECT 'Ha' -- Do Stuff
DELETE @tempPFRunStops WHERE ProformaRunStopsID = (SELECT TOP 1 ProformaRunStopsID FROM @tempPFRunStops)
END
Here is the one of the better solutions.
DECLARE @i int
DECLARE @curren_val int
DECLARE @numrows int
create table #Practitioner (idx int IDENTITY(1,1), PractitionerId int)
INSERT INTO #Practitioner (PractitionerId) values (10),(20),(30)
SET @i = 1
SET @numrows = (SELECT COUNT(*) FROM #Practitioner)
IF @numrows > 0
WHILE (@i <= (SELECT MAX(idx) FROM #Practitioner))
BEGIN
SET @curren_val = (SELECT PractitionerId FROM #Practitioner WHERE idx = @i)
--Do something with Id here
PRINT @curren_val
SET @i = @i + 1
END
Here i've add some values in the table beacuse, initially it is empty.
We can access or we can do anything in the body of the loop and we can access the idx by defining it inside the table definition.
BEGIN
SET @curren_val = (SELECT PractitionerId FROM #Practitioner WHERE idx = @i)
--Do something with Id here
PRINT @curren_val
SET @i = @i + 1
END
Although cursors usually considered horrible evil I believe this is a case for FAST_FORWARD cursor - the closest thing you can get to FOREACH in TSQL.
Suppose that the column PractitionerId is a unique, then you can use the following loop
DECLARE @PractitionerId int = 0
WHILE(1 = 1)
BEGIN
SELECT @PractitionerId = MIN(PractitionerId)
FROM dbo.Practitioner WHERE PractitionerId > @PractitionerId
IF @PractitionerId IS NULL BREAK
SELECT @PractitionerId
END
I would say everything probably works except that the column idx
doesn't actually exist in the table you're selecting from. Maybe you meant to select from @Practitioner
:
WHILE (@i <= (SELECT MAX(idx) FROM @Practitioner))
because that's defined in the code above like that:
DECLARE @Practitioner TABLE (
idx smallint Primary Key IDENTITY(1,1)
, PractitionerId int
)
This generally (almost always) performs better than a cursor and is simpler:
DECLARE @PractitionerList TABLE(PracticionerID INT)
DECLARE @PracticionerID INT
INSERT @PractitionerList(PracticionerID)
SELECT PracticionerID
FROM Practitioner
WHILE(1 = 1)
BEGIN
SET @PracticionerID = NULL
SELECT TOP(1) @PracticionerID = PracticionerID
FROM @PractitionerList
IF @PracticionerID IS NULL
BREAK
PRINT 'DO STUFF'
DELETE TOP(1) FROM @PractitionerList
END
Your select count and select max should be from your table variable instead of the actual table
DECLARE @i int
DECLARE @PractitionerId int
DECLARE @numrows int
DECLARE @Practitioner TABLE (
idx smallint Primary Key IDENTITY(1,1)
, PractitionerId int
)
INSERT @Practitioner
SELECT distinct PractitionerId FROM Practitioner
SET @i = 1
SET @numrows = (SELECT COUNT(*) FROM @Practitioner)
IF @numrows > 0
WHILE (@i <= (SELECT MAX(idx) FROM @Practitioner))
BEGIN
SET @PractitionerId = (SELECT PractitionerId FROM @Practitioner WHERE idx = @i)
--Do something with Id here
PRINT @PractitionerId
SET @i = @i + 1
END
I made a procedure that execute a FOREACH
with CURSOR
for any table.
Example of use:
CREATE TABLE #A (I INT, J INT)
INSERT INTO #A VALUES (1, 2), (2, 3)
EXEC PRC_FOREACH
#A --Table we want to do the FOREACH
, 'SELECT @I, @J' --The execute command, each column becomes a variable in the same type, so DON'T USE SPACES IN NAMES
--The third variable is the database, it's optional because a table in TEMPB or the DB of the proc will be discovered in code
The result is 2 selects for each row.
The syntax of UPDATE
and break the FOREACH
are written in the hints.
This is the proc code:
CREATE PROC [dbo].[PRC_FOREACH] (@TBL VARCHAR(100) = NULL, @EXECUTE NVARCHAR(MAX)=NULL, @DB VARCHAR(100) = NULL) AS BEGIN
--LOOP BETWEEN EACH TABLE LINE
IF @TBL + @EXECUTE IS NULL BEGIN
PRINT '@TBL: A TABLE TO MAKE OUT EACH LINE'
PRINT '@EXECUTE: COMMAND TO BE PERFORMED ON EACH FOREACH TRANSACTION'
PRINT '@DB: BANK WHERE THIS TABLE IS (IF NOT INFORMED IT WILL BE DB_NAME () OR TEMPDB)' + CHAR(13)
PRINT 'ROW COLUMNS WILL VARIABLE WITH THE SAME NAME (COL_A = @COL_A)'
PRINT 'THEREFORE THE COLUMNS CANT CONTAIN SPACES!' + CHAR(13)
PRINT 'SYNTAX UPDATE:
UPDATE TABLE
SET COL = NEW_VALUE
WHERE CURRENT OF MY_CURSOR
CLOSE CURSOR (BEFORE ALL LINES):
IF 1 = 1 GOTO FIM_CURSOR'
RETURN
END
SET @DB = ISNULL(@DB, CASE WHEN LEFT(@TBL, 1) = '#' THEN 'TEMPDB' ELSE DB_NAME() END)
--Identifies the columns for the variables (DECLARE and INTO (Next cursor line))
DECLARE @Q NVARCHAR(MAX)
SET @Q = '
WITH X AS (
SELECT
A = '', @'' + NAME
, B = '' '' + type_name(system_type_id)
, C = CASE
WHEN type_name(system_type_id) IN (''VARCHAR'', ''CHAR'', ''NCHAR'', ''NVARCHAR'') THEN ''('' + REPLACE(CONVERT(VARCHAR(10), max_length), ''-1'', ''MAX'') + '')''
WHEN type_name(system_type_id) IN (''DECIMAL'', ''NUMERIC'') THEN ''('' + CONVERT(VARCHAR(10), precision) + '', '' + CONVERT(VARCHAR(10), scale) + '')''
ELSE ''''
END
FROM [' + @DB + '].SYS.COLUMNS C WITH(NOLOCK)
WHERE OBJECT_ID = OBJECT_ID(''[' + @DB + '].DBO.[' + @TBL + ']'')
)
SELECT
@DECLARE = STUFF((SELECT A + B + C FROM X FOR XML PATH('''')), 1, 1, '''')
, @INTO = ''--Read the next line
FETCH NEXT FROM MY_CURSOR INTO '' + STUFF((SELECT A + '''' FROM X FOR XML PATH('''')), 1, 1, '''')'
DECLARE @DECLARE NVARCHAR(MAX), @INTO NVARCHAR(MAX)
EXEC SP_EXECUTESQL @Q, N'@DECLARE NVARCHAR(MAX) OUTPUT, @INTO NVARCHAR(MAX) OUTPUT', @DECLARE OUTPUT, @INTO OUTPUT
--PREPARE TO QUERY
SELECT
@Q = '
DECLARE ' + @DECLARE + '
-- Cursor to scroll through object names
DECLARE MY_CURSOR CURSOR FOR
SELECT *
FROM [' + @DB + '].DBO.[' + @TBL + ']
-- Opening Cursor for Reading
OPEN MY_CURSOR
' + @INTO + '
-- Traversing Cursor Lines (While There)
WHILE @@FETCH_STATUS = 0
BEGIN
' + @EXECUTE + '
-- Reading the next line
' + @INTO + '
END
FIM_CURSOR:
-- Closing Cursor for Reading
CLOSE MY_CURSOR
DEALLOCATE MY_CURSOR'
EXEC SP_EXECUTESQL @Q --MAGIA
END
The following line is wrong in your version:
WHILE (@i <= (SELECT MAX(idx) FROM @Practitioner))
(Missing the @)
Might be an idea to change your naming convention so that the tables are more different.
Source: Stackoverflow.com