[278] fix nested where clauses missing parantheses

Author: ahmad-moussawi

QueryBuilder.Tests/GeneralTests.cs

@@ -386,5 +386,20 @@ public void Can_Change_Generic_Offset_After_SpecificLimit()
             Assert.Equal("SELECT * FROM `mytable` LIMIT 5 OFFSET 7", c[EngineCodes.MySql].ToString());
             Assert.Equal("SELECT * FROM \"mytable\" LIMIT 20 OFFSET 7", c[EngineCodes.PostgreSql].ToString());
         }
+
+        [Fact]
+        public void Where_Nested()
+        {
+            var query = new Query("table")
+            .Where(q => q.Where("a", 1).OrWhere("a", 2));
+
+            var engines = new[] {
+                EngineCodes.SqlServer,
+            };
+
+            var c = Compilers.Compile(engines, query);
+
+            Assert.Equal("SELECT * FROM [table] WHERE ([a] = 1 OR [a] = 2)", c[EngineCodes.SqlServer].ToString());
+        }
     }
 }

QueryBuilder/Compilers/Compiler.Conditions.cs

@@ -174,7 +174,7 @@ protected virtual string CompileNestedCondition<Q>(SqlResult ctx, NestedConditio
 
             var sql = CompileConditions(ctx, clauses);
 
-            return x.IsNot ? $"NOT ({sql})" : sql;
+            return x.IsNot ? $"NOT ({sql})" : $"({sql})";
         }
 
         protected string CompileTwoColumnsCondition(SqlResult ctx, TwoColumnsCondition clause)