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SQLLinter/Infrastructure/Rules/UpperLowerRule.cs

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+using Microsoft.SqlServer.TransactSql.ScriptDom;
+using SQLLinter.Common;
+
+namespace SQLLinter.Infrastructure.Rules;
+
+public class UpperLowerRule : BaseRuleVisitor, IRule
+{
+
+    public override string Text => "Использование функций UPPER или LOWER при выполнении сравнений в операторах SELECT не требуется при запуске базы данных в режиме без учета регистра.";
+
+    public override void Visit(SelectStatement node)
+    {
+        var visitor = new ChildQueryComparisonVisitor();
+        node.Accept(visitor);
+        if (visitor.QueryExpressionUpperLowerFunctionFound)
+        {
+            AddViolation(node);
+        }
+    }
+
+    public class ChildQueryComparisonVisitor : TSqlFragmentVisitor
+    {
+        public bool QueryExpressionUpperLowerFunctionFound { get; private set; }
+
+        public override void Visit(QueryExpression node)
+        {
+            var visitor = new ChildBooleanComparisonVisitor();
+            node.Accept(visitor);
+            if (visitor.UpperLowerFunctionCallInComparison)
+            {
+                QueryExpressionUpperLowerFunctionFound = true;
+            }
+        }
+    }
+
+    public class ChildBooleanComparisonVisitor : TSqlFragmentVisitor
+    {
+        public bool UpperLowerFunctionCallInComparison { get; private set; }
+
+        public override void Visit(BooleanComparisonExpression node)
+        {
+            var visitor = new ChildFunctionCallVisitor();
+            node.Accept(visitor);
+            if (visitor.UpperLowerFound)
+            {
+                UpperLowerFunctionCallInComparison = true;
+            }
+        }
+    }
+
+    public class ChildFunctionCallVisitor : TSqlFragmentVisitor
+    {
+        public bool UpperLowerFound { get; private set; }
+
+        public override void Visit(FunctionCall node)
+        {
+            if (node.FunctionName.Value.Equals("UPPER", StringComparison.OrdinalIgnoreCase) ||
+                node.FunctionName.Value.Equals("LOWER", StringComparison.OrdinalIgnoreCase))
+            {
+                UpperLowerFound = true;
+            }
+        }
+    }
+}