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# File 'lib/batchagg.rb', line 101
def self.sql(relation, defn)
q = relation.except(:select)
t = q.model.arel_table
case defn.type
when :count
q.select(Arel.star.count).to_sql
when :count_expression
q.select(Arel.sql("COUNT(#{defn.expression})")).to_sql
when :count_distinct
q.select(t[defn.column].count(true)).to_sql
when :count_distinct_expression
q.select(Arel.sql("COUNT(DISTINCT #{defn.expression})")).to_sql
when :sum
q.select(Arel::Nodes::NamedFunction.new("COALESCE", [t[defn.column].sum, Arel::Nodes.build_quoted(0)])).to_sql
when :sum_expression
q.select(Arel.sql("COALESCE(SUM(#{defn.expression}), 0)")).to_sql
when :avg
q.select(Arel::Nodes::NamedFunction.new("COALESCE", [t[defn.column].average, Arel::Nodes.build_quoted(0.0)])).to_sql
when :avg_expression
q.select(Arel.sql("COALESCE(AVG(#{defn.expression}), 0.0)")).to_sql
when :min
q.select(Arel::Nodes::NamedFunction.new("COALESCE", [t[defn.column].minimum, Arel::Nodes.build_quoted(0)])).to_sql
when :min_expression
q.select(Arel.sql("COALESCE(MIN(#{defn.expression}), 0)")).to_sql
when :max
q.select(Arel::Nodes::NamedFunction.new("COALESCE", [t[defn.column].maximum, Arel::Nodes.build_quoted(0)])).to_sql
when :max_expression
q.select(Arel.sql("COALESCE(MAX(#{defn.expression}), 0)")).to_sql
when :string_agg
delim = defn.options&.dig(:delimiter)
args = [t[defn.column]]
args << Arel::Nodes.build_quoted(delim) if delim
q.select(Arel::Nodes::NamedFunction.new("GROUP_CONCAT", args)).to_sql
when :string_agg_expression
delim = defn.options&.dig(:delimiter)
args = [Arel.sql(defn.expression)]
args << Arel::Nodes.build_quoted(delim) if delim
q.select(Arel::Nodes::NamedFunction.new("GROUP_CONCAT", args)).to_sql
else
raise "Unknown aggregate type: #{defn.type}"
end
end
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