diff --git a/semester4/dmdb/data-modelling-databases-summary.pdf b/semester4/dmdb/data-modelling-databases-summary.pdf
index 09960b7..511c4ea 100644
Binary files a/semester4/dmdb/data-modelling-databases-summary.pdf and b/semester4/dmdb/data-modelling-databases-summary.pdf differ
diff --git a/semester4/dmdb/data-modelling-databases-summary.tex b/semester4/dmdb/data-modelling-databases-summary.tex
index cc2a903..9678811 100644
--- a/semester4/dmdb/data-modelling-databases-summary.tex
+++ b/semester4/dmdb/data-modelling-databases-summary.tex
@@ -46,6 +46,7 @@ A note on the quote on the title page: He did not \textit{actually} mean ``curry
 \newsection
 \section{SQL}
 \input{parts/00_sql/00_intro.tex}
+\input{parts/00_sql/01_operations.tex}
 
 
 
diff --git a/semester4/dmdb/parts/00_sql/01_operations.tex b/semester4/dmdb/parts/00_sql/01_operations.tex
index 5e6adff..54cb887 100644
--- a/semester4/dmdb/parts/00_sql/01_operations.tex
+++ b/semester4/dmdb/parts/00_sql/01_operations.tex
@@ -27,3 +27,6 @@ After \texttt{GROUP BY} we can't use \texttt{WHERE}, instead we can use \texttt{
 We can compare against a query with a single result column and row using a \texttt{WHERE} clause.
 
 The \texttt{CROSS JOIN} is the both-sided extension to \texttt{LEFT JOIN} and \texttt{RIGHT JOIN}
+
+We can compute the number of all passed grades for a person using something like
+\mint{sql}+SUM(CASE Grade >= 1 THEN 1 ELSE 0 END) AS PassedSubjectsCount+