Question

I keep getting the following error:

Msg 241, Level 16, State 1, Line 9 Conversion failed when converting
datetime from character string.

Here is the code I am trying to execute:

  DECLARE @v_sql  varchar(max),
  @v_database varchar(25),
  @vStartTime     DATETIME,
  @vEndTime       DATETIME

SELECT @v_database = N'[DATABASE_NAME]', @vStartTime = '2012-09-27', @vEndTime = '2012-11-27'


SELECT @v_sql = N'SELECT
  (SELECT ID FROM DATASTORE.DBO.PLANT WHERE DESCRIPTION = ''Henderson''),
  SEQ, 
  AID, 
  NAME, 
  GRP, 
  AREA, 
  PRIO,
  CASE ITIME WHEN ''-'' THEN NULL ELSE CAST(SUBSTRING(ITIME,1,8) + '' '' + SUBSTRING(ITIME,9,2) + '':'' + SUBSTRING(ITIME,11,2) + '':'' + SUBSTRING(ITIME,13,2) AS DATETIME) END ITIME,
  CASE ATIME WHEN ''-'' THEN NULL ELSE CAST(SUBSTRING(ATIME,1,8) + '' '' + SUBSTRING(ATIME,9,2) + '':'' + SUBSTRING(ATIME,11,2) + '':'' + SUBSTRING(ATIME,13,2) AS DATETIME) END ATIME,
  CASE NTIME WHEN ''-'' THEN NULL ELSE CAST(SUBSTRING(NTIME,1,8) + '' '' + SUBSTRING(NTIME,9,2) + '':'' + SUBSTRING(NTIME,11,2) + '':'' + SUBSTRING(NTIME,13,2) AS DATETIME) END NTIME,
  DUR, 
  MSG,
  VAR1,
  VAR2,
  VAR3,
  VAR4, 
  OPR, 
  USER_COMMENT
FROM ' + @v_database + '.PROD.ALARM
WHERE CAST(substring(ITIME, 1, 4) + ''-'' + substring(ITIME, 5, 2) + ''-'' + substring(ITIME, 7, 2) + '' '' + substring(ITIME,9,2) + '':'' + substring(ITIME,11,2) + '':'' + substring(ITIME,13,2) + substring(ITIME,15,3) AS DATETIME) BETWEEN  ' + @vStartTime +' AND ' + @vEndTime + ' ORDER BY ITIME'
EXEC(@v_sql)

Any help would be much appreciated, I am looking into this for a co-worker and it’s got us both stumped.

Edit with a bit more digging, we were able to resolve it ourselves, passing parameters to sp_executesql:

declare
  @vSql     NVARCHAR(MAX),
  @vParam    NVARCHAR(MAX),
  @vDatabase       VARCHAR(15)

SET @vParam = '@vStartTime DATETIME, @vEndTime DATETIME'

 SELECT @vSql = '
    SELECT ''
      '+ @vDatabase + ''',
      ITEM_CODE,
      SOURCE,
      DEST,
      TRAN_DT,
      MILL_NAME,
      NULL
    FROM ' + @vDatabase + '.PROD.GRD_LOG
    WHERE TRAN_DT BETWEEN @vStartTime AND @vEndTime'

EXEC sp_executesql @vSql, @vParam, @vStartTime, @vEndTime

By making the variables NVARCHAR(MAX), and then using sp_executesql instead of just executing the @vSql variable, we were able to resolve our issue.

Thanks to anyone who might have been looking into this.

Answer 1

In your original dynamic SQL, you were trying to add datetime variable to a text string which results in SQL attempting to convert the text string to a datetime value (by the order of precedence of conversion). You need to set the variables to nvarchar as well to avoid conversion in the original dynamic SQL.