A sequence is an ordered set consisting of some data, which are called members of the sequence. A sequence is similar to an array in high-level languages, but the data types of its members not necessarily the same. The following will explain its basic computation through creation, access, operators and functions.
1.Cre...
2015-01-07 874 0
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During our dealing with the database transactions, some operations may produce errors which could bring unexpected results, particularly during batch processes. In order to prevent this from happening, we need to manage the data connection in a right way and handle those errors properly.
1. Database error messages
Firs...
2015-01-06 1129 0
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After data are imported from a data table, we often need to group them as required, or work out grouping and summarizing result. In esProc, groups function is used to compute the result of data grouping and summarizing; or group function can be used to first group the data, then perform further analysis and computation...
2015-01-06 1264 0
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In esProc, the storage of cellset variables is ubiquitous. Cell values are convenient references during computation, but they could occupy too much memory. Data can be cleared from cells to reduce memory footprint after they accomplish their mission in computation. It should be particularly noted that, when the interme...
2015-01-05 961 0
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The usual way to insert summary values into the grouped data is to process data group by group. Import a group of data, append them and their summary value to a new file and then do the same with the next group, and so on. But it is not easy to realize this in hard coding. esProc, however, supports group cursor with wh...
2015-01-05 1118 0
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Table sequences are universally used in esProc. During data analysis and computing, we often need to add records to a table sequence or delete them from it, or modify the data in it. This article will illustrate the modification and maintenance of the table sequences through operations of adding, deleting and modifying...
2015-01-04 946 0
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In esProc, we can use not only the SQL to retrieve data from databases, but also the preliminary database query results to perform further analyses and operations to solve some complicated problems which are difficult to deal with in SQL alone.
1. Database connection and disconnection
When SQL accesses databases, it sh...
2014-12-30 1264 0
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We often need to sort or rank data during data statistics and analysis. The operations include problems like sort sales records according to the dates and rank the results of salespersons for assessing their performance.
1. Sort and rank members in a sequence
In esProc, functions, such as psort, sort, ranki rank, and e...
2014-12-30 1069 0
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Java programs can call esProc via JDBC. It is necessary for programmers to know how to deploy the esProc JDBC and familiarize themselves with the detailed configuration information.
1． Basic steps
The following instructions need to be followed to deploy the esProc JDBC:
1) Load necessary jars
Load the jars needed by es...
2014-12-29 1659 0
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In esProc, strings are not merely a data type; they can also be used as macros or string constants to construct expressions, or employed by eval() function to generate expressions dynamically as needed.
1. Macro
Macros in esProc refer to strings for composing expressions, only that these strings are usually generated d...
2014-12-26 1027 0
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In esProc Getting Started: Types of Cells, we learned that cells in esProc have many types, including constant cell, computational cell, executable cell and comment cell, and etc. The code blocks into which code is written in esProc also have the similar types: computational block, assignment block, executable block an...
2014-12-25 991 0
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The command line refers to using commands in the form of strings in DOS-like environment to execute programs. All operating systems support the command lines, like the Linux console and the Windows command line window.
The file, esprocx.exe, is needed when the command line is used to execute an esProc cellset file. The...
2014-12-24 1558 0
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Besides data tables, store procedures are also very important for a database. esProc can call database stored procedures conveniently. This article will illustrate in detail how to call various stored procedures with db.proc() function in esProc.
1. Call stored procedures without return values
Stored procedu...
2014-12-23 1045 0
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Sometimes we need to fetch certain data from multiple files of a multi-level directory during text processing. The operation is too complicated to be well performed at the command line. Though it can be realized in high-level languages, the code is difficult to write; and the involvement of big files will increase the ...
2014-12-22 1148 0
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3. No result or multiple results
It is allowed to return no result during calling a cellset file. Take the following cellset file – outputData1.dfx – as an example:
A
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$(demo) select * from CITIES
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=A1.select(Arg.pos(left(NAME,1))>0)
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=file(“Cities.txt”)
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>A3.export@t...
2014-12-18 1062 0
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