Help With SQL 1

[JavaToPerlNowVB]

I am trying to rebuild some of the old Queries in old database and I came accross with this

SELECT gl_maint_action.glfwm_key, [description] & IIf(IsNull([com_a]),""," (" & [com_a] & ")") & IIf(IsNull([com_b]),""," (" & [com_b] & ")") AS [Desc]
FROM gl_maint_action INNER JOIN gl_maint_code ON gl_maint_action.maint_code = gl_maint_code.maint_code;

What I don't understand is this part

[description] & IIf(IsNull([com_a]),""," (" & [com_a] & ")") & IIf(IsNull([com_b]),""," (" & [com_b] & ")")

I am not sure if anyone can help with this or it has enough information for somebody to understand.

Thanks alot

 

[NSNewey]

Hi JavaToPerlNowVB

The IIf function returns one of two parts, depending on the evaluation of an expression.

Syntax

IIf(expr, truepart, falsepart)

Your code appears to return a zero length string ("") if com_a is null or com_a in brackets if it is not null. This is the same for com_b and they both get appended to the [description] field. Therefore, if [description] is "Plastic Cup" and [com_a] is "colour red" the return would be "Plastic Cup (Colour Red)" or just "Plastic Cup" if [com_a] has no value.

Hope this helps.