Difference between revisions of "Multiply sets"
| Line 12: | Line 12: | ||
</source> | </source> | ||
<div> | <div> | ||
| − | In this example we are attempting to see how much money has been obtained over 4 | + | <p>In this example we are attempting to see how much money has been obtained over 4 |
| − | years due to interest. | + | years due to interest.</p> |
| − | As the added up rate is not accurate 5 + 4 + 5 + 3 = 17% | + | <p>As the added up rate is not accurate 5 + 4 + 5 + 3 = 17%</p> |
| − | We need to instead find the logarithm of the compound interest and then we need to sum that. | + | <p>We need to instead find the logarithm of the compound interest and then we need to sum that.</p> |
| − | SELECT SUM(LN((rate/100)+1)) FROM interest | + | <p>SELECT SUM(LN((rate/100)+1)) FROM interest</p> |
| − | Then we inverse or take the exponent of the logarithm with | + | <p>Then we inverse or take the exponent of the logarithm with</p> |
| − | SELECT EXP(SUM(LN((rate/100)+1))) FROM interest | + | <p>SELECT EXP(SUM(LN((rate/100)+1))) FROM interest</p> |
| − | and then finally to get the amount after 4 years we times this amount by 100 ($100). | + | <p>and then finally to get the amount after 4 years we times this amount by 100 ($100).</p> |
</div> | </div> | ||
<source lang='sql' class='def'>SELECT EXP(SUM(LN((rate/100)+1)))*100 | <source lang='sql' class='def'>SELECT EXP(SUM(LN((rate/100)+1)))*100 | ||
Revision as of 11:59, 30 July 2012
Multiply across a result set.
DROP TABLE interest
CREATE TABLE interest( yr INTEGER, rate INTEGER ); INSERT INTO interest VALUES (2002,5); INSERT INTO interest VALUES (2003,4); INSERT INTO interest VALUES (2004,5); INSERT INTO interest VALUES (2005,3);
In this example we are attempting to see how much money has been obtained over 4 years due to interest.
As the added up rate is not accurate 5 + 4 + 5 + 3 = 17%
We need to instead find the logarithm of the compound interest and then we need to sum that.
SELECT SUM(LN((rate/100)+1)) FROM interest
Then we inverse or take the exponent of the logarithm with
SELECT EXP(SUM(LN((rate/100)+1))) FROM interest
and then finally to get the amount after 4 years we times this amount by 100 ($100).
SELECT EXP(SUM(LN((rate/100)+1)))*100 FROM interest
Hack 10 Converting subqueries into joins
Hack 11 Converting aggregate subqueries into joins
Hack 16 Search for a String across columns
Hack 24 Multiply Across a Result Set
Hack 25.5 Splitting and combining columns
Hack 26 Include the rows your JOIN forgot
Hack 30 Calculate the maximum/minimum of two fields
Hack 33 Get values and subtotals in one shot
Hack 50 Combine tables containing different data
Hack 51/52 Display rows as columns
Hack 55 Import Someone Else's Data
Hack 62 Issue Queries Without Using a Table
Hack 63 Generate rows without tables
Hack 72 Extract a subset of the results
Hack 78 Break it down by Range
Hack 88 Test two values from a subquery
