Access to T-SQL query conversion - What to use in place of the IIf() function?

My query is as follows : I have written in access can anyone pls help how can I convert it into sql query I am getting an error near IIF condition.

SELECT #NT_VAR_STEP_1_1.SYS_ID, #NT_VAR_STEP_1_1.NODE, #NT_VAR_STEP_1_1.TEMP_ID,
       #NT_VAR_STEP_1_1.EQUIP_TYPE, #NT_VAR_STEP_1_1.EQ_ID,
       #NT_VAR_STEP_1_1.VAR_ID, #NT_VAR_STEP_1_1.NODE AS VAR_SET,
       #NT_VAR_STEP_1_1.VAR_NAME, IIf([#NT_VAR_STEP_1_1]![VAR_SUBSET]=‘SELF’,
       [#NT_VAR_STEP_1_1]![NODE],[#NT_VAR_STEP_1_1]![VAR_SUBSET]) AS VAR_SUBSET,

 IIf([#NT_VAR_STEP_1_1]![EQUIP_TYPE]=‘SOURCE’,’PARAMVAR’,’VAR’) AS CALC_VAR_TYPE,

       #NT_VAR_STEP_1_1.VAR_DATA_TYPE AS DATA_TYPE, #NT_VAR_STEP_1_1.DOF,
       #NT_VAR_STEP_1_1.RETAIN, #NT_VAR_STEP_1_1.COEFF_OBJECT,
       #NT_VAR_STEP_1_1.COEFF_VAR_SET, #NT_VAR_STEP_1_1.COEFF_VAR_TYPE,
       #NT_VAR_STEP_1_1.COEFF_VAR_SUBSET, #NT_VAR_STEP_1_1.COEFF_VAR_NAME,
       #NT_VAR_STEP_1_1.OPERAND, #NT_VAR_STEP_1_1.SIGN,
       #NT_VAR_STEP_1_1.VAR_TP_OFFSET, #NT_VAR_STEP_1_1.COEFF_TP_OFFSET,
       #NT_VAR_STEP_1_1.COEFF_VAR_SUBTYE INTO #OT_VAR_STEP_1_1_1
FROM #NT_VAR_STEP_1_1
GROUP BY #NT_VAR_STEP_1_1.SYS_ID, #NT_VA开发者_运维百科R_STEP_1_1.TEMP_ID,
         #NT_VAR_STEP_1_1.EQUIP_TYPE, #NT_VAR_STEP_1_1.EQ_ID,
         #NT_VAR_STEP_1_1.VAR_ID, #NT_VAR_STEP_1_1.NODE,
         #NT_VAR_STEP_1_1.VAR_NAME, IIf([#NT_VAR_STEP_1_1]![VAR_SUBSET]=‘SELF’,
         [#NT_VAR_STEP_1_1]![NODE],[#NT_VAR_STEP_1_1]![VAR_SUBSET]),

         IIf([#NT_VAR_STEP_1_1]![EQUIP_TYPE]=‘SOURCE’,’PARAMVAR’,’VAR’),

         #NT_VAR_STEP_1_1.VAR_DATA_TYPE, #NT_VAR_STEP_1_1.DOF,
         #NT_VAR_STEP_1_1.RETAIN, #NT_VAR_STEP_1_1.COEFF_OBJECT,
         #NT_VAR_STEP_1_1.COEFF_VAR_SET, #NT_VAR_STEP_1_1.COEFF_VAR_TYPE,
         #NT_VAR_STEP_1_1.COEFF_VAR_SUBSET, #NT_VAR_STEP_1_1.COEFF_VAR_NAME,
         #NT_VAR_STEP_1_1.OPERAND, #NT_VAR_STEP_1_1.SIGN,
         #NT_VAR_STEP_1_1.VAR_TP_OFFSET, #NT_VAR_STEP_1_1.COEFF_TP_OFFSET,
         #NT_VAR_STEP_1_1.COEFF_VAR_SUBTYE, #NT_VAR_STEP_1_1.NODE
HAVING (((#NT_VAR_STEP_1_1.EQUIP_TYPE)<>‘COST_NODE’));

Convert this line:

IIf([#NT_VAR_STEP_1_1]![EQUIP_TYPE]=‘SOURCE’,’PARAMVAR’,’VAR’) AS CALC_VAR_TYPE

to this:

CASE WHEN [#NT_VAR_STEP_1_1].[EQUIP_TYPE]='SOURCE'
  THEN 'PARAMVAR'
  ELSE 'VAR'
END CALC_VAR_TYPE

And then use the same in your GROUP BY clause, but without the column alias:

CASE WHEN [#NT_VAR_STEP_1_1].[EQUIP_TYPE]='SOURCE'
  THEN 'PARAMVAR'
  ELSE 'VAR'
END

I will assume you're going to SQL Server (T-SQL). T-SQL does not support IIF, you will need to use CASE instead.