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Oracle9i OLAP Developer's Guide to the OLAP DML
Release 2 (9.2)

Part Number A95298-01
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Working with Expressions, 4 of 11

Specifying a Single Value for the Dimension of an Expression

A qualified data reference (QDR) is a way of limiting one or more dimensions of an expression to a single value. QDRs are useful when you want to specify a single value without changing the current status. Using a QDR, you can qualify a dimension (which allows you to specify one dimension value in an expression) or one or more dimensions of a variable or relation.

A qualified data reference takes the following form.

expression(dimname1 dimexp1 [, dimname2 dimexp2. . .])

The dimname argument is the name of one of the dimensions, or a dimension surrogate of the dimension, of the expression and the dimexp argument is one of the following:

Qualifying a Variable

You can qualify any or all of a dimensions of a variable using either of the following techniques:

For example, the variable sales has three dimensions, month, product, and district. You might want to compare total sales in Boston to the total sales in all cities. In a single command, you want district to be limited to two different values:

The command below lets you calculate this result by using a QDR.

SHOW sales(district 'BOSTON')/TOTAL(sales)

You can qualify more than one of the dimensions of a variable. For example, if you qualify all the dimensions of the sales variable by specifying one dimension value of each dimension, then you narrow sales down to a single-cell value.

To fetch sales for JUN02, TENTS, and SEATTLE, use the following QDR.

SHOW sales(month 'JUN02', product 'TENTS', district 'SEATTLE')

This command fetches a single value.

You can use a qualified data reference with the target expression of the = command. This lets you assign a value to a specific cell in a data object.

The following example assigns the value 10200 to the data cell of the sales composite that is specified in the qualified data reference. If the composite named sales does not already have a value for the combination BOSTON and TENTS, then this value combination is added to the composite, thus adding the data cell.

sales(market 'BOSTON' product 'TENTS' month 'JAN99')= 10200

Replacing a Dimension in a Variable

When you use a relation as the qualifier in the QDR, you replace a dimension of the variable with the dimension or dimensions of the relation. The relation must be related to the dimension that you are qualifying, and it must be dimensioned by the replacement dimension.

Example 4-1 Replacing a Dimension in a Variable

Suppose you have two variables, sales and quota, which are dimensioned by month, product, and district. A third variable, division.mgr, is dimensioned by month and division. You also have a relation between division and product, called division.product. These objects have the following definitions.

LD Sales Revenue

The command below produces the report following it.

REPORT division.mgr

DIVISION  JAN02    FEB02    MAR02    APR02    MAY02    JUN02   
--------  -------- -------- -------- -------- -------- --------
CAMPING   Hawley   Hawley   Jones    Jones    Jones    Jones   
SPORTING  Carey    Carey    Carey    Carey    Carey    Musgrave
CLOTHING  Musgrave Musgrave Musgrave Musgrave Musgrave Wong    

Suppose you want to obtain a report that shows the fraction by which sales have exceeded quota; and you want to include the appropriate division manager for each product. You can show the division manager for each product by using the relation division.product, which is related to division and dimensioned by product, as the qualifier. The QDR replaces the division dimension with product, so that it has the same dimensions as the other expression in the report "sales / quota." The command below produces the report following it.

REPORT DOWN month sales W 6 sales/quota W 8 HEADING -
   'MANAGER' division.mgr(division division.product)

        ----TENTS---- ---CANOES---- --RACQUETS---  --SPORTSWEAR-- ---FOOTWEAR---
        SALES/        SALES/        SALES/         SALES/         SALES/
------  ----- ------- ----- ------- ----- -------  ----- -------- ----- --------
JAN02   1.00  Hawley  0.82  Hawley  1.02  Carey    0.91  Musgrave 0.92  Musgrave
FEB02   0.84  Hawley  0.96  Hawley  1.00  Carey    0.80  Musgrave 1.07  Musgrave
MAR02   0.87  Jones   0.95  Jones   0.87  Carey    0.88  Musgrave 0.91  Musgrave
APR02   0.91  Jones   0.93  Jones   0.99  Carey    0.94  Musgrave 0.95  Musgrave

Qualifying a Relation

You can also use a QDR to qualify a relation (which is really a special kind of variable).

Suppose the region.district relation is dimensioned by district. If you qualify district with the value SEATTLE, then the value of the expression is the value of the relation for SEATTLE. Because the QDR specifies one value of district, the expression has a single-cell result.

The definition of region.district is as follows.

LD The region for each district

The command below displays the value WEST.

SHOW region.district(district 'SEATTLE')

Qualifying a Dimension

You can use a QDR to qualify the dimension itself, which allows you to specify one dimension value in an expression. The following expression specifies one value of district, the one contained in the single-cell variable mydistrict.

district(district mydistrict)

For a concat dimension, you can use a QDR to qualify the dimension by specifying a value from one of the base dimensions of the concat dimension. The following expression specifies one value of reg.dist.ccdim, a concat dimension that has region and district as its base dimensions. The costs variable is dimensioned by the division and reg.dist.ccdim dimensions.

show reg.dist.ccdim(district 'BOSTON')

The preceding expression produces the following result.


Using Ampersand Substitution with QDRs

An ampersand character (&) at the beginning of an expression substitutes the value of the expression for the expression itself in a command or function.When you use an ampersand with a QDR, you must enclose the whole expression in parentheses if you want the variable to be qualified before the substitution is made.

Suppose you have a text variable named myvar that is dimensioned by reptype and that contains the names of variables. Remember that it is myvar that is dimensioned by reptype, not the variables named by myvar. Therefore, you must use parentheses so that myvar is qualified and the resulting value is used in the REPORT command.

REPORT &(myvar(reptype 'ACTUAL'))

If you do not use parentheses and the variable that is specified in myvar is sales, then you will get an error message that sales is not dimensioned by reptype.

Using the QUAL Function to Specify a QDR

Sometimes you will find that the syntax of a QDR is ambiguous and could either be misinterpreted or cause a syntax error. In this case, you can use the QUAL function to explicitly specify a qualified data reference (QDR).

Example 4-2 Using the QUAL Function

The following example first shows how you might view your data by limiting its dimensions, and then how you might view it by using QUAL.

These commands produce the report shown below them.

LIMIT month TO 'JAN96' TO 'JUN96'
REPORT DOWN month W 11 MAX(actual,budget) W 11 actual W 11 budget

MONTH            BUDGET)     ACTUAL      BUDGET
-------------- ----------- ----------- -----------
JAN96           287,557.87  287,557.87  279,773.01
FEB96           323,981.56  315,298.82  323,981.56
MAR96           326,184.87  326,184.87  302,177.88
APR96           394,544.27  394,544.27  386,100.82
MAY96           449,862.25  449,862.25  433,997.89
JUN96           457,347.55  457,347.55  448,042.45

Now consider how you might view the same figures for MAX(actual,budget) without changing the status of line or division.

LIMIT month TO 'JAN96' TO 'JUN96'
REPORT HEADING 'For Cogs in Sporting Division' DOWN month -
   W 11 HEADING 'MAX(actual,budget)'-
   QUAL(MAX(actual,budget), line 'COGS', division 'SPORTING')

For Cogs in
Sporting       MAX(ACTUAL,
Division         BUDGET)
-------------- -----------
JAN96           287,557.87
FEB96           323,981.56
MAR96           326,184.87
APR96           394,544.27
MAY96           449,862.25
JUN96           457,347.55

If you attempt to produce the same report with standard QDR syntax, then an error is signalled.

REPORT HEADING 'For Cogs in Sporting Division' DOWN month -
   W 11 HEADING 'MAX(actual,budget)'-
   MAX(actual,budget) (line cogs, division sporting)

The following error message is produced.

ERROR: A right parenthesis or an operator is expected after LINE.

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