In Excel, formulas can be automatically worked out according to their relative positions while being copied. This works well in continuous cells, but formulas are usually wrong when the operation is performed in incontinuous cells. The computation between multilayered summaries is the latter case.
It is comparatively e...
2014-11-19 887 0
0
During database application development, we often need to deal with complicated SQL-style computations. The transposition of rows and columns is one of them. Oracle uses pivot function to realize this computation. The other databases haven’t the counterparts to realize it directly, which makes the corresponding code di...
2014-11-19 886 0
0
The operation of getting the top N rows of data is common, such as the biggest salary raise of each employee, the three lowest scores in playing golf and the five days of each month when each product has its biggest sales. SQL resorts to advanced techniques, like window functions and keep/top/row number, to solve this ...
2014-11-18 838 0
0
There is a type of text files that they are too big to be entirely loaded into the memory, yet as the data have been sorted by a certain column and if they are imported in groups according to this column, they can be all put into the memory for computing. These text files include the call detail record of a telecom com...
2014-11-17 841 0
0
During database application development, we often need to handle complicated SQL-style computations. Data grouping with fixed criteria is just one type of these. It refers to the computation whose grouping criteria not come from the to-be-grouped data, but from the outside, such as another table, the external parameter...
2014-11-14 1121 0
0
It is common to group and summarize data in a spreadsheet in data statistics. Through data manipulation in Excel, we can group, summarize, sort or filter data. But it is complicated to process data which has been grouped and summarized in an Excel spreadsheet, because we need to perform the operation on data block of e...
2014-11-12 871 0
0
As Java doesn’t directly support dynamically parsing expressions in the text files, the computation can only be realized by splitting strings manually and then writing a recursive program. The whole process requires writing a great amount of code, is complicated and the code is difficult to maintain. With the assistanc...
2014-11-11 863 0
0
It is rather inconvenient to summarize details in Excel. You can only enter the formulas by hand when beyond-the-group computation is involved, which is not only a laborious job but also easy to get wrong. This is because Excel lacks the smart adjustment mechanism and only supports copying formulas mechanically accordi...
2014-11-07 858 0
0
As languages for data computations, both esProc and R language have rich functions to process text files. They have many similarities in basic usage, as well as obvious differences, such as in the aspect of processing files with fixed column width and big text files, reading and writing designated columns, computationa...
2014-11-06 899 0
0
During developing database applications, we are often faced with complicated SQL-style computations like relational computation on multilayered groups. As SQL requires summarizing during data grouping and it doesn’t support object-style relational access, it is difficult to deal with these computations. We have to reso...
2014-11-03 844 0
0
In developing database applications, usually it is the records corresponding to the max/min value that we need to retrieve, instead of the value itself. For example, the occasion in which each employee gets his/her biggest pay raise; the three lowest scores ever got in golf; the five days in each month when each produc...
2014-10-31 857 0
0
esProc can help Java deal with various computations in processing structured texts. But in the case of non-single row records, it is necessary to preprocess the data before esProc can perform computations on it.
Let’s look at this through an example. The text file Social.txt is the access records of a website, in which...
2014-10-31 894 0
0
It is simple for Java to sort data in text files of small size. But when big files are involved, you need to import data segmentally, write out the sorting result of each segment in temporary files and at last, merge these temporary files. The programming will be rather complicated. Even if the file is small enough to ...
2014-10-30 832 0
0
Following problems will arise if you perform conditional filtering on text files in Java alone:
1. The text file is not a database,soit cannot be accessed by SQL. The code needs to be modified if filtering conditions are changed. Besides, if you want a flexible conditional filtering as that in SQL, you have to self-pro...
2014-10-30 875 0
0
Grouping and summarizing data in sheets is what we often need to do during performing data analysis and statistics. We can group and summarize data in Excel, but actually, it is seldom that this function is used. Reasons for this include several aspects: Excel is strict about the format of data to be grouped and summar...
2014-10-29 886 0
0
