SQL Join taking long time

Question

I have two tables

(1) MonthlyTarget {SalesManCode, TargetMonthYear, TargetValue}; this table has 1966177 rows.

(2) MonthlySales  {SalesManCode, SaleDate, AchievedValue};

this table has 400310 rows.

I have to make a query that produces a result like the following table:

{SalesManCode, JanTar, JanAch, FebTar, FebAch,....., DecTar, DecAch}

The problem is, joining these two tables taking a long time.

What should be the query?

How can the query be optimized?

I don't want to consider indexing.

Answer 1

It looks like you're missing some columns in your MonthlyTarget table, namely a "TargetDate" column.

In addition to what everyone has already said about indexing, sometimes a divide-and-conquer approach can really help. Rather than joining a 1966177 row table to a 400310 row table, create to tiny temp tables and join them together instead:

CREATE TABLE #MonthlySalesAgg
(
    SalesManCode int,
    JanTar money,
    FebTar money,
    MarTar money,
    AprTar money,
    MayTar money,
    JunTar money,
    JulTar money,
    AugTar money,
    SepTar money,
    OctTar money,
    NovTar money,
    DecTar money

    PRIMARY KEY CLUSTERED (SalesManCode)
)

INSERT INTO #MonthlySalesAgg
SELECT *
FROM
(SELECT SalesManCode, TargetValue, SaleMonth = Month(TargetDate) FROM MonthlyTarget) as temp
PIVOT
(
    Max(TargetValue)
    FOR [SaleMonth] IN ([1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12])
) as p

CREATE TABLE #MonthlyTargetAgg
(
    SalesManCode int,
    JanAch money,
    FebAch money,
    MarAch money,
    AprAch money,
    MayAch money,
    JunAch money,
    JulAch money,
    AugAch money,
    SepAch money,
    OctAch money,
    NovAch money,
    DecAch money

    PRIMARY KEY CLUSTERED (SalesManCode)
)

INSERT INTO #MonthlyTargetAgg
SELECT * FROM
(SELECT SalesManCode, AchievedValue, SaleMonth = Month(SaleDate) FROM MonthlySales) as temp
PIVOT
(
    Sum(AchievedValue)
    FOR [SaleMonth] IN ([1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12])
) as p

The queries above create two intermediate tables which should contain the same number of records as your SalesMan table. Joining them is straightforward:

SELECT *
FROM #MonthlyTargetAgg target
INNER JOIN #MonthlySalesAgg sales ON target.SalesManCode = sales.SalesManCode

If you find yourself needing to pull out data by month all the time, move the code into a view instead.

PIVOT requires SQL Server 2005 or higher, and its often a very useful operator. Hopefully SQL Server 2008 will allow users to pivot on more than one column at a time, which will result in an even simpler query than shown above.

Using SQL Server 2000:

PIVOT is syntax sugar. For example,

SELECT * FROM
(SELECT SalesManCode, AchievedValue, SaleMonth = Month(SaleDate) FROM MonthlySales) as temp
PIVOT
(
    Sum(AchievedValue)
    FOR [SaleMonth] IN ([1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12])
) as p

Becomes

SELECT
    SalesManCode,
    [1] = Sum(case SaleMonth when 1 then AchievedValue else 0 end),
    [2] = Sum(case SaleMonth when 2 then AchievedValue else 0 end),
    [3] = Sum(case SaleMonth when 3 then AchievedValue else 0 end),
    [4] = Sum(case SaleMonth when 4 then AchievedValue else 0 end),
    [5] = Sum(case SaleMonth when 5 then AchievedValue else 0 end),
    [6] = Sum(case SaleMonth when 6 then AchievedValue else 0 end),
    [7] = Sum(case SaleMonth when 7 then AchievedValue else 0 end),
    [8] = Sum(case SaleMonth when 8 then AchievedValue else 0 end),
    [9] = Sum(case SaleMonth when 9 then AchievedValue else 0 end),
    [10] = Sum(case SaleMonth when 10 then AchievedValue else 0 end),
    [11] = Sum(case SaleMonth when 11 then AchievedValue else 0 end),
    [12] = Sum(case SaleMonth when 12 then AchievedValue else 0 end)
FROM
    (SELECT SalesManCode, AchievedValue, SaleMonth = Month(SaleDate) FROM MonthlySales) as temp
GROUP BY SalesManCode