HAVING COUNT(*) > 3: This clause filters the groups formed by the GROUP BY clause based on an aggregate condition. The HAVING clause is similar to the WHERE clause, but it is used with aggregate functions like COUNT(). Here, it filters the groups where the count of rows in each group...
After introducing SQL-type null values, their impact on the translation is thoroughly investigated, resulting in several extensions of the translation. A translation experiment with many queries shows that the proposed translation method generates optimized relational algebra expressions. It is shown that ...
aThe upper left window is the window of the relational algebra expression Das obere linke Fenster ist das Fenster des Verwandtschaftsalgebraausdruckes[translate] aMobline Mobline[translate] aThe programme controller allows so-called temperature profiles to be worked with, i.e. selected heating-up,...
Functional completeness of a relational language is the ability to express linear recursive queries. We present such a language that also has the property of relational completeness (relational algebra is, in fact, embedded in it). The transitive closure of a binary relation is carried out by ...