We are often confronted with complicated SQL-style computations during developing data base applications. For instance, arrange grouped data into one column in certain order, making marks for different types of groups and detail data, as shown in the following:
This kind of operation is commonly seen in organizing rep...
2014-10-28 257 0
Java provides only the most basic data import functions like specifying separators. But other common functions, such as importing specified columns by column names, specifying the order of columns and data types and that no separator should be used, need to be realized manually. Though they are not difficult to realize...
2014-10-28 231 0
JoinRowSet and FilteredRowSet provided by RowSet– Java’s class library for data computing – can perform cross-database related computing, but they have a lot of weaknesses. First, JoinRowSet only supports inner join, it doesn’t support outer join. Second, test shows that db2, mysql and hsql can work with JoinRowSet, ye...
2014-10-27 287 0
Generally, Java programmers use poi or other open source packages to read and compute Excel data. These open source packages support low-level programming, which increases the overall learning cost and complicates the operation. But with the help of esProc, Java can avoid these problems.
An example will make the point ...
2014-10-24 23740 0
It is not difficult for Java to access HDFS through API provided by Hadoop. But to realize computations, like grouping, filtering and sorting, on files in HDFS in Java is troublesome. esProc is a good helper in Java’s dealing with these computations. It can execute the access to HDFS too. With the help of esProc, Java ...
2014-10-23 248 0
Sometimes you are required to sort the detailed data in a spreadsheet. However, the sorting is difficult to realize due to the inflexible operation in Excel. You have to sort the data by groups, which requires quite a lot of work.
But you can perform the operation more easily in esCalc. Let’s look at an example. Summa...
2014-10-23 250 0
Java’s JSON open source package can only parse JSON data and hasn’t the computational function. It is troublesome for programmers to develop a general program for performing computations, such as grouping, sorting, filtering and joining, by themselves. For example, during developing program for performing conditional f...
2014-10-22 289 0
It is easy for Java to connect to Hive using JDBC. But the computational ability of Hive is less than that of SQL in other databases. So to deal with uncommon computations, data should be retrieved before further operation is performed using Java. Thus the code for will be complicated.
But if esProc is used to help wit...
2014-10-21 388 0
For a programming language for desktop data analysis, the most important is that it must be user-friendly and have great computing power. We can judge whether a language is suitable for analyzing data on desktop from six aspects: application environment, file processing, text and string processing, structured data proc...
2014-10-20 270 0
MongoDB does not support join directly.The unity JDBC recommended by the official website can perform the join operation after retrieving data out. But the advanced functions, like join, group, functions and expressions, are only provided by the paid version of unity JDBC. Even the paid version does not support the com...
2014-10-16 289 0
Recently, we skillfully handled an industry project to import a great amount of data from file to Oracle in comparatively short time.
At the beginning, we tried to import the data with the sqlldr of Oracle, only to find it is surprisingly time-consuming to load a great amount of data: Too slow if 2.5 hours have to be s...
2014-10-14 245 0
Essentially, the main content of various data analyses in our routine business is the structured data computing. For example:
A. Compute the link relative ratio and year-on-year comparison of each business branch’s monthly sales during a specified period of time.
Implementation approach: filter the sales data by time r...
2014-10-13 263 0
Following problems will arise if you perform conditional filtering on text files in Java alone:
1. The text file is not a database, so it cannot be accessed by SQL. The code needs to be modified if the expression of grouping and summarizing is changed. Besides, if you want a flexible expression, you have to self-progra...
2014-10-01 377 0
tbl.insert(5,value1:col1,value2:col2,……) //Insert a record preceding Row 5
In Perl, to insert an element into an array, it may be easy if this is at the beginning, where shift and unshift functions are available, for example:
@array = (“one”...
2014-09-30 281 0
Loop function can traverse every member of an array or a set, express complicated loop statements with simple functions, as well as reduce the amount of code and increase readability. Both esProc and R language support the loop function. The following will compare their similarities and differences in usage.
2014-09-29 270 0