getting error while converting to date time in stored procedure - sql

Question

I am getting error like:
Msg 241, Level 16, State 1, Procedure spQueryMgt, Line 106 [Batch
Start Line 13] Conversion failed when converting date and/or time
from character string.
ALTER PROCEDURE [dbo].[spQueryMgt]
#Mode varchar(50)='',
#Query_Form varchar(20)='',
#Patient_ID bigint=0,
#Verified_By bigint = 0,
#Verified_Date datetime=''
AS
BEGIN
IF(#mode='Post_Query')
BEGIN
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'Update '+ CONVERT(varchar(12), #Query_Form) +' Set
Verified_By='+CONVERT(VARCHAR(12), #Verified_By)+',
Verified_Date='''+CONVERT(datetime, #Verified_Date,20)+'''
where Patient_ID = '+CONVERT(varchar(12), #Patient_ID)
EXEC sp_executeSQL #sql;
END
END

Answer 1

Change your query to -
SET #sql = N'Update '+ CONVERT(varchar(12), #Query_Form) +' Set
Verified_By='+CONVERT(VARCHAR(12), #Verified_By)+',
Verified_Date='''+CONVERT(VARCHAR(20), #Verified_Date,20)+'''
where Patient_ID = '+CONVERT(varchar(12), #Patient_ID)
There is issue with your convert function. You are converting #Verified_Date to datetime and concatenating datetime to varchar string.

Answer 2

The problem was that you where converting datetime back into datetime, and then tried to concatinate which gives you that exception.
But also, by initializing parameters to '' and 0 you are filling your database with unnesesary values like '' for varchars and 1900-01-01 for datetime columns and even worse 0 in integer columns.
Is that what you really want ? I doubt it.
It will be impossible to determine if a field was intentionaly set to this value or was left empty and get you into troubles later.
You can do your procedure like this to get NULL values in empty parameters
ALTER PROCEDURE [dbo].[spQueryMgt] (
#Mode varchar(50) = NULL,
#Query_Form varchar(20) = NULL,
#Patient_ID bigint = NULL,
#Verified_By bigint = NULL,
#Verified_Date datetime = NULL
)
AS
BEGIN
SET NOCOUNT ON;
IF #mode ='Post_Query'
BEGIN
DECLARE #sql NVARCHAR(MAX);
if (#Query_Form is not null) and (#Patient_ID is not null) -- nu use in updating when no table or id is given
begin
SET #sql = N' Update ' + CONVERT(varchar(12), #Query_Form) +
' Set Verified_By = ' + isnull(CONVERT(VARCHAR(12), #Verified_By), 'null') + ',' +
' Verified_Date = ' + case when #Verified_Date is null then 'null' else '''' + CONVERT(varchar(20), #Verified_Date, 20) + '''' end +
' where Patient_ID = ' + isnull(CONVERT(varchar(12), #Patient_ID), 'null')
EXEC sp_executeSQL #sql;
end
END
END
EDIT
As mentioned in the comments you should also take care of sql injection, and that makes your procedure safer, but also even easier
create PROCEDURE [dbo].[spQueryMgt] (
#Mode varchar(50) = NULL,
#Query_Form varchar(20) = NULL,
#Patient_ID bigint = NULL,
#Verified_By bigint = NULL,
#Verified_Date datetime = NULL
)
AS
BEGIN
SET NOCOUNT ON
IF #mode = 'Post_Query'
BEGIN
DECLARE #sql NVARCHAR(MAX)
if (#Query_Form is not null) and (#Patient_ID is not null) -- nu use in updating when no table or id is given
begin
SET #sql = N'Update #P0 ' +
'set Verified_By = #P1, ' +
' Verified_Date = #P2 ' +
'where Patient_ID = #P3'
EXEC sp_executesql #sql,
N'#P0 varchar(20), #P1 bigint, #P2 bigint, #P3 datetime',
N'#P0 = #Query_Form, #P1 = #Verified_By, #P2 = #Verified_Date, #P3 = #Patient_ID'
end
END
END