ggregate functions perform a calculation on a set of values and return a single value. Aggregate function avg( ) only calculate average without null values. It provides average result, eliminating null values. Null does not have a value (and is not a member of any data domain) but it is a placeholder or "mark" for missing information. Comparisons with Null can never result in either True or False but always in the third logical result is Unknown. So comparing two null is difficult. We discus about
(1) review of the research for handling null values in database system using aggregate function (2) problem structure with null value with respect to database (3) describes existing solution and proposed solution and its algorithm as well as how it works (4) details the experimental work that has been carried out. The experimental evaluation has been performed using a large amount of datasets.
From comparison table we see that our propose system takes less times than existing system. By proposed system can reduce time and reduce the problem of existing system. To understand easily a graph chart is given below.
Our propose solution is efficient to calculate average value with Null values from large amount of data.
From the above graph Green bar indicates Existing solution time and Red Bar indicates proposed solution time. We see that in proposed system needs execution time less than existing system. VIII.
At the age of globalization most of all bank already has been computerized. They store their customer information, balance, transaction etc. in database. And they need to calculate average number of transaction after a certain period of time. Even stock exchange Ltd. Hospital, Airlines etc. need to calculate average number of transaction frequently. So our proposed system will be best for them which can save their times.
| VI. | ||
| Amount of | Existing solution | Proposed Solution |
| Data | Execution Time (sec) | Execution Time (sec) |
| 40000 | 0.2840 | 0.2460 |
| 80000 | 0.5720 | 0.5040 |
| 120000 | 0.8440 | 0.8250 |
| 160000 | 1.1841 | 1.1591 |
| 180000 | 1.3301 | 1.3011 |
| 200000 | 1.5511 | 1.5011 |
| 220000 | 1.7511 | 1.5781 |
| 240000 | 1.9371 | 1.7641 |
| 260000 | 2.0601 | 1.9671 |
| 280000 | 2.1851 | 2.0762 |
V.
In this solution we see that if the number of data in database gradually increased then the execution time is increased. Built
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