If k (a single field or a combination of fields) is table M’s primary key, and k, at the same time, exists in table B, then k is regarded as B’s foreign key. The foreign key defines a relationship between two tables and is one of the most important concepts for structured data computing. Through object references, esPr...
2015-05-27 499 0
We learned how to plot a dot chart element using logical coordinates in esProc Charts: The Dot Element. Here we’ll learn about plotting the line element. The line element is another one of the most basic chart elements, which is positioned by at least two pairs of logical coordinates. If there are more logical coordina...
2015-05-26 593 0
In esProc Charts: Coordinate Axes, we learned the basic usages of different coordinate axes and the setting of their properties. Once a logical axis is properly defined, the logical coordinates on it can be transformed into corresponding physical coordinates, according to which a certain chart element can be plotted.
2015-05-22 603 0
We talked about different types of coordinate axis used in esProc in esProc Charts: Coordinate Axes and learned that a chart element can be plotted on the coordinate plane after defining a pair of axes. From this article, we’ll discuss how to plot a chart according to specified position starting from the simplest dot e...
2015-05-20 624 0
In esProc Charts: Coordinate Systems and Coordinate Transformation, we discussed the relation between logical axes and physical axes in plotting a chart with esProc, as well as how to position an axis and a chart element on the canvas. esProc provides a variety of logical axes for plotting different styles of charts. L...
2015-05-18 618 0
Regarding the chart element plotting, compared with setting the appearance properties for a chart element like color and line style, it is more important to specify its position. When plotting a chart, statistical values are often used to determine its position. Therefore you will need to create a coordinate system on ...
2015-05-14 590 0
In databases, creating appropriate indexes for tables can greatly increase query efficiency. Similarly, index sequences can be created for record sequences or table sequences in esProc to increase efficiency in querying data repeatedly.
For example, we need to access the food order Order_Foods.txt repeatedly.
2015-05-13 419 0
With esProc, you can handle the structured big data easily, and perform data computing and analysis without difficulty. Because the big data table cannot be loaded into the memory all at once, the basic solution is using cursor to handle it.
1. Basic principle of cursor
The esProc cursor is like the database cursor in ...
2015-05-12 429 0
1. Foreign key referencing
The foreign key is a common concept for various relational databases. In a relational table, you can define one or multiple fields as the foreign key. The foreign key field values can be associated with the data in another table. For example, in the game scoring report, player scores are usua...
2015-05-11 606 0
1. Sequences and sets in esProc
Unlike traditional programming languages, esProc employs sets commonly. In fact, the sequence in esProc belongs to the field of set. So it’s quite important to deeply understand the concept of sets when using esProc. Like an integer and a string, the set is a basic esProc data type; it c...
2015-05-07 424 0
esProc provides standard JDBC to integrate with BIRT and other reporting tools. Here we’ll explain the process of integration of esProc and BIRT in development environment and WEB application environment.
1. Integration in development environment
1.1 Create configuration files
Create the two configuration files –...
2015-04-27 1258 0
1. File encryption
esProc provides ways of encrypting cellset files to protect them from unauthorized access or use. There are two levels of encryption:
Execution privilege：By this privilege, users can set parameters, execute the cellset and see the cell values; they can also view the cellset descriptions and cell tips...
2015-04-24 389 0
esProc provides flexible charting functionality. It allows users to define parameters and data used for charting with the graphics editor, and to draw various styles of charts as needed using drawing functions.
1. General charting procedure
Let’s learn of the general procedure of charting in esProc through the followin...
2015-04-23 538 0
1. Accessing members
Members in a set of esProc (sequence) are organized in order. Therefore, you can reference a member in a set with its sequence number. The more flexible use of sequence numbers, the better esProc functions to make operations simpler and more efficient. Thus sequence numbers or an integer sequence (...
2015-04-02 539 0
In esProc, loop computation works on each member of a sequence, or each record of a table sequence and a record sequence. Now the computation can be completed with simple loop functions, instead of the loop statements.
1. Loop computation
While performing loop computation on a sequence, you can reference sequence membe...
2015-03-27 398 0