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While importing the structured text files into the database using Java alone, we need to combine the SQL statements together manually, and to deal with various troublesome situations as well, like if the data in a table has been existed, whether we should update it or insert data into it, if some fields are included in the file, and if the fields in the file are consistent with those in the table.
As esProc participates in Java programming, these problems can be solved…Continue
Added by Lynn Guo on December 22, 2014 at 7:04pm — No Comments
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 company, statistics of visitors on a website, information of members of a shopping mall, etc.
A great deal of complicated code, which is difficult to maintain, is…Continue
Added by Lynn Guo on December 15, 2014 at 6:24pm — No Comments
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 assistance of esProc, we can develop program for the computation in Java without writing code manually. Let’s look at how esProc works through an example.
Here is a text…Continue
Added by Lynn Guo on December 10, 2014 at 6:30pm — No Comments
During developing the database applications, we often need to perform computations on the grouped data in each group. For example, list the names of the students who have published papers in each of the past three years; make statistics of the employees who have taken part in all previous training; select the top three days when each client gets the highest scores in a golf game; and the like. To perform these computations, SQL needs multi-layered nests, which will…Continue
Added by Lynn Guo on December 3, 2014 at 6:30pm — No Comments
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 product gets its highest sales amount; and so on. As the max function of SQL can only retrieve the max value, instead of the records to which the max…Continue
Added by Lynn Guo on December 1, 2014 at 6:05pm — No Comments