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правки
Изменения
→Примеры
Переменные:
S <font color = grey>::</font> Students<font color = grey>;</font> G <font color = grey>::</font> Groups<font color = grey>;</font> C <font color = grey>::</font> Courses<font color = grey>;</font> P <font color = grey>::</font> Point<font color = grey>;</font>
G4 <font color = grey>::</font> Groups <font color = blue>where </font> Name <font color = grey>=</font> <font color = green>'M34351'</font> <font color = blue> ∨</font> Name <font color = grey>=</font> <font color = green>'M34371'</font> <font color = blue> ∨ </font> Name <font color = grey>=</font> <font color = green>'M34391'</font>
Полностью аттестованные группы:
<font color = blue>select </font> G<font color = grey>.</font>GId <font color = blue>from </font> G <font color = blue>where ∀S </font> <font color = blue>$\forall$</font>S <font color = grey>(</font>∀C <font color = blue>$\forall$</font>C <font color = grey>(</font>∃P<font color = blue>$\exists$</font>P <font color = grey>(</font>S<font color = grey>.</font>SId <font color = grey>=</font> P<font color = grey>.</font>SId ∧ <font color = blue>$\land$</font> C<font color = grey>.</font>CId <font color = grey>=</font> P<font color = grey>.</font>CId ∧ <font color = blue>$\land$</font> P<font color = grey>.</font>Points <font color = blue>≥ </font> 60<font color = grey>)))</font>
Несколько отношений:
<font color = blue>select </font> S<font color = grey>.</font>FirstName<font color = grey>,</font> S<font color = grey>.</font>LastName<font color = grey>,</font> G<font color = grey>.</font>Name <font color = blue>from </font> S<font color = grey>,</font> G <font color = blue>where </font> S<font color = grey>.</font>GId <font color = grey>=</font> G<font color = grey>.</font>GId
