Joining multiple columns in one table to a single column in another table - sql

Question

I am looking to create a view that pulls data from two tables "Schedule" and "Reference".
Schedule has 50+ columns (it's almost completely denormalized -- not my design), most of which contain a value that could be joined to a column in the Reference table.
How do I write the SQL statement to correctly join each column in Schedules to the single column in Reference?
The Schedule table is defined as:
CREATE TABLE [dbo].[Schedule](
[ID] [int] NOT NULL,
[SCHEDULEWEEK] [datetime] NOT NULL,
[EMPNO] [numeric](10, 0) NOT NULL,
[EMPLNAME] [varchar](32) NULL,
[EMPFNAME] [varchar](32) NULL,
[EMPSENDATE] [datetime] NULL,
[EMPHIREDATE] [datetime] NULL,
[EMPTYPE] [char](1) NULL,
[EMPSTATUS] [char](1) NULL,
[SNREFUSALS] [tinyint] NULL,
[QUALSTRING] [varchar](128) NULL,
[JOBOVERSHIFTTYPE] [bit] NULL,
[SHORTNOTICE] [bit] NULL,
[SHORTNOTICEWAP] [bit] NULL,
[SHORTNOTICEPHONE] [varchar](32) NULL,
[LEADHAND] [bit] NULL,
[DUALCURRENCY] [bit] NULL,
[MIN100WINDOW] [bit] NULL,
[STATHOLIDAY] [bit] NULL,
[AREAOVERHOURS] [bit] NULL,
[DOUBLEINTERZONES] [bit] NULL,
[MAXDAYSPERWEEK] [tinyint] NULL,
[MAXHOURSPERWEEK] [numeric](10, 2) NULL,
[MAXHOURSPERSHIFT] [numeric](10, 2) NULL,
[MAXDOUBLESPERWEEK] [tinyint] NULL,
[ASSIGNEDDAYS] [tinyint] NULL,
[ASSIGNEDHOURS] [numeric](10, 2) NULL,
[ASSIGNEDDOUBLES] [tinyint] NULL,
[ASSIGNEDLOAHOURS] [numeric](10, 2) NULL,
[SHIFTNO1] [int] NULL,
[TEXT1_1] [varchar](64) NULL,
[TEXT2_1] [varchar](64) NULL,
[DAYFLAG1] [bit] NULL,
[COMMENT1] [text] NULL,
[SHIFTNO2] [int] NULL,
[TEXT1_2] [varchar](64) NULL,
[TEXT2_2] [varchar](64) NULL,
[DAYFLAG2] [bit] NULL,
[COMMENT2] [text] NULL,
[SHIFTNO3] [int] NULL,
[TEXT1_3] [varchar](64) NULL,
[TEXT2_3] [varchar](64) NULL,
[DAYFLAG3] [bit] NULL,
[COMMENT3] [text] NULL,
[SHIFTNO4] [int] NULL,
[TEXT1_4] [varchar](64) NULL,
[TEXT2_4] [varchar](64) NULL,
[DAYFLAG4] [bit] NULL,
[COMMENT4] [text] NULL,
[SHIFTNO5] [int] NULL,
[TEXT1_5] [varchar](64) NULL,
[TEXT2_5] [varchar](64) NULL,
[DAYFLAG5] [bit] NULL,
[COMMENT5] [text] NULL,
[SHIFTNO6] [int] NULL,
[TEXT1_6] [varchar](64) NULL,
[TEXT2_6] [varchar](64) NULL,
[DAYFLAG6] [bit] NULL,
[COMMENT6] [text] NULL
-- Snip
) ON [PRIMARY]
And the Reference table is defined as:
CREATE TABLE [dbo].[Reference](
[ID] [int] NOT NULL,
[CODE] [varchar](21) NOT NULL,
[LOCATIONCODE] [varchar](4) NOT NULL,
[SCHAREACODE] [varchar](16) NOT NULL,
[LOCATIONNAME] [varchar](32) NOT NULL,
[FLTAREACODE] [varchar](16) NOT NULL
) ON [PRIMARY]
I am trying to join each [TEXT1_]/[TEXT2_] column in Schedule to the [SCHAREACODE] column in reference. All the reference table contains is a list of areas where the employee could work.

Answer 1

I think he means to join on the Reference table multiple times:
SELECT *
FROM Schedule AS S
INNER JOIN Reference AS R1
ON R1.ID = S.FirstID
INNER JOIN Reference AS R2
ON R2.ID = S.SecondID
INNER JOIN Reference AS R3
ON R3.ID = S.ThirdID
INNER JOIN Reference AS R4
ON R4.ID = S.ForthID

Answer 2

Your description is a bit lacking, so I'm going to assume that
Schedule has 50+ columns (it's almost completely denormalized -- not my design), most of which contain a value that could be joined to a column in the Reference table.
means that 1 of the 50+ columns in Schedule is a ReferenceId. So, given a table design like:
Schedule ( MaybeReferenceId1, MaybeReferenceId2, MaybeReferenceId3, ... )
Reference ( ReferenceId )
Something like:
SELECT *
FROM Schedule
JOIN Reference ON
Schedule.MaybeReferenceId1 = Reference.ReferenceId
OR Schedule.MaybeReferenceId2 = Reference.ReferenceId
OR Schedule.MaybeReferenceId3 = Reference.ReferenceId
OR Schedule.MaybeReferenceId4 = Reference.ReferenceId
...
would work. You could simplify it by using IN if your RDBMS supports it:
SELECT *
FROM Schedule
JOIN Reference ON
Reference.ReferenceId IN (
Schedule.MaybeReferenceId1,
Schedule.MaybeReferenceId2,
Schedule.MaybeReferenceId3,
Schedule.MaybeReferenceId4,
...
)

Answer 3

From updated question
Perhaps something like this? It will be messy no matter what you do.
SELECT S.ID
S.TEXT1_1,
TEXT1_1_RID = COALESCE((SELECT MAX(R.ID) FROM Reference R WHERE R.SCHAREACODE = S.TEXT1_1), 0),
S.TEXT1_2,
TEXT1_2_RID = COALESCE((SELECT MAX(R.ID) FROM Reference R WHERE R.SCHAREACODE = S.TEXT1_2), 0),
...
FROM Schedule S

Answer 4

Agree with TheSoftwareJedi, but can I just suggest using LEFT JOINs so that failures-to-match don't cause your Schedule row to disappear?
Of course, doing 28 JOINs is going to be a bit cumbersome whatever the details.
I'm not sure I'd call this "denormalized", more "abnormalized" ... :-)

Answer 5

Try a query like this:
select s.*, r.schareacode from schedule s,
where
s.text1_1 = s.schareacode
or s.text2_1 = s.schareacode
or s.textx_x = s.schareacode
..
You should be able to get the same results with traditional joins so I recommend you experiment with that as well.