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SQLLinter/Infrastructure/Rules/DistinctRule.cs

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+using Microsoft.SqlServer.TransactSql.ScriptDom;
+using SQLLinter.Common;
+
+namespace SQLLinter.Infrastructure.Rules;
+
+public class DistinctRule : BaseRuleVisitor
+{
+    public override string Text => "Избегать DISTINCT, отдавать предпочтение GROUP BY.";
+
+    public override void Visit(SelectStatement node)
+    {
+        var query = node.QueryExpression as QuerySpecification;
+        if (query != null && query.SelectElements.Any() && query.UniqueRowFilter == UniqueRowFilter.Distinct)
+        {
+            AddViolation(node);
+        }
+    }
+}