Tag Archive for 'computer science'

MySQL: group_concat allows you to easily concatenate the grouped values of a row

Last week I stumbled over a really useful function in MySQL: group_concat allows you to concatenate the data of one column of multiple entries by grouping them by one field field. You can choose the separator to use for the concatenation. The full syntax is as follows:

GROUP_CONCAT([DISTINCT] expr [,expr ...]
             [ORDER BY {unsigned_integer | col_name | expr}
                 [ASC | DESC] [,col_name ...]]
             [SEPARATOR str_val])

According to the MySQL documentation, the function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values. To eliminate duplicate values, use the DISTINCT clause. To sort values in the result, use the ORDER BY clause. To sort in reverse order, add the DESC (descending) keyword to the name of the column you are sorting by in the ORDER BY clause.

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Model-Driven Development – Modellierung mit UML2

OMG UML LogoIm Rahmen meines Studiums der Informatik an der TU Kaiserslautern habe ich das Proseminars “Model Driven Development” der Arbeitsgruppe Software Engineering AGSE erfolgreich absolviert und mich mit dem Thema “Modellierung mit UML 2″ beschäftigt. Die Ausarbeitung als auch die Vortragsfolien stelle ich hier zum download bereit.

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