What's wrong with my SQL query?

Question

SELECT id, 
       sageaccount, 
       sageid, 
       totalwithoutvat, 
       vat, 
       total, 
       invoicedate, 
       alloweditting, 
       finished, 
       CASE WHEN isposted = 1 THEN 'Posted on ' + posteddate 
           ELSE 'Not Posted' 
       END AS Posted 
FROM Invoices 
WHERE (sageaccount = @sageaccount)

If I take the '+ posteddate' away, it works perfectly. But with the + posteddate, I get this error:

Conversion failed when converting datetime from character string.

The posteddate field is usually null, unless posted is true, and the format of posteddate is definetly datetime.

Any ideas?

Answer 1

You need to convert posteddate to a varchar value in order to concatenate it with another varchar value ('Posted on ')

SELECT  id, 
        sageaccount, 
        sageid, 
        totalwithoutvat, 
        vat, total, 
        invoicedate, 
        alloweditting, 
        finished, 
        CASE WHEN isposted = 1 THEN 'Posted on ' + CONVERT(varchar(10), posteddate, 20) ELSE 'Not Posted' END AS Posted 
FROM Invoices 
WHERE (sageaccount = @sageaccount)

Answer 2

I suspect it is complaining about you trying to add a date to a string. Depending on what platform you are using:

1) Ensure that string concatenation can be achieved with '+'. You might have to call a function instead such as CONCAT()

2) Cast the Date as a string.

Answer 3

You are adding two values with different types, so the database tries to convert one of them to the other type.

Convert the datetime value to a string before concatenating:

SELECT
  id, sageaccount, sageid, totalwithoutvat, vat, total,
  invoicedate, alloweditting, finished,
  CASE
    WHEN isposted = 1 THEN 'Posted on ' + convert(varchar, posteddate)
    ELSE 'Not Posted'
  END AS Posted
FROM Invoices
WHERE sageaccount = @sageaccount

Answer 4

the PostedDate must be treated as a string first before you can join it to another string. You can do a conversion this way

CONVERT(varchar(10), posteddate, 101)

Syntax for CONVERT: CONVERT ( data_type [ ( length ) ] , expression [ , style ] )

style is optional

here are some samples of styles:

101 = mm/dd/yyyy ex. 01/02/1999

102 = yy.mm.dd ex. 99.02.01

103 = dd/mm/yyyy ex. 02/01/1999