相当于Oracle的Access / jet解码

Question

Is there an equivalent for Oracle's decode() in Access (or Jet, for that matter).

The problem I am facing is: I should sort (order) a resultset based basically upon a status and a date (with all records having status = 2) at the end.

In Oracle I'd go something like

select
  ...
from
  ...
where
  ..
order by
  decode(status, 2, 0, 1),
  date_column

Answer 1

The closest analogy is the SWITCH() function eg

Oracle:

SELECT supplier_name,
       decode(supplier_id,  10000, 'IBM',
                            10001, 'Microsoft',
                            10002, 'Hewlett Packard',
                                   'Gateway') result
  FROM suppliers;

Access Database Engine

SELECT supplier_name,
       SWITCH(supplier_id = 10000, 'IBM',
              supplier_id = 10001, 'Microsoft',
              supplier_id = 10002, 'Hewlett Packard',
              TRUE, 'Gateway') AS result
  FROM suppliers; 

Note that with the SWITCH() function you have to supply the full predicate each time, so you are not restricted to using just supplier_id. For the default value, use a predicate that is obvious to the human reader that it is TRUE eg 1 = 1 or indeed simply TRUE :)

Something that may not be obvious is that the logic in the SWITCH() function doesn't short circuit, meaning that every expression in the function must be able to be evaluated without error. If you require logic to short circuit then you will need to use nested IIF() functions.

Answer 2

You can try with IIF. See this stackoverflow question.

Answer 3

I think it might compare to switch or choose.

Switch(expr-1, value-1[, expr-2, value-2 … [, expr-n,value-n]])

-- http://office.microsoft.com/en-us/access/HA012289181033.aspx

Choose(index, choice-1[, choice-2, ... [, choice-n]])

-- http://msdn.microsoft.com/en-us/library/aa262690%28VS.60%29.aspx

Answer 4

You can use the SWITCH function:

LABEL: Switch(
   [TABLE_NAME]![COL_NAME]='VAL1';'NEW_VAL1';
   [TABLE_NAME]![COL_NAME]='VAL2';'NEW_VAL2';
)

Note semicolons and not commas.

The example above works in queries in MS Access 2010.