Iss 581 where exists remove select

QueryBuilder.Tests/SelectTests.cs

@@ -903,5 +903,33 @@ public void SelectWithFilter()
  Assert.Equal("SELECT [Title], SUM(CASE WHEN [Published_Month] = 'Jan' THEN [ViewCount] END) AS [Published_Jan], SUM(CASE WHEN [Published_Month] = 'Feb' THEN [ViewCount] END) AS [Published_Feb] FROM [Posts]", sqlServer.ToString());
  }
 
+ [Fact]
+ public void SelectWithExists()
+ {
+ var q = new Query("Posts").WhereExists(
+ new Query("Comments").WhereColumns("Comments.PostId", "=", "Posts.Id")
+ );
+
+ var sqlServer = Compilers.CompileFor(EngineCodes.SqlServer, q);
+ Assert.Equal("SELECT * FROM [Posts] WHERE EXISTS (SELECT 1 FROM [Comments] WHERE [Comments].[PostId] = [Posts].[Id])", sqlServer.ToString());
+ }
+
+ [Fact]
+ public void SelectWithExists_OmitSelectIsFalse()
+ {
+ var q = new Query("Posts").WhereExists(
+ new Query("Comments").Select("Id").WhereColumns("Comments.PostId", "=", "Posts.Id")
+ );
+
+
+ var compiler = new SqlServerCompiler
+ {
+ OmitSelectInsideExists = false,
+ };
+
+ var sqlServer = compiler.Compile(q).ToString();
+ Assert.Equal("SELECT * FROM [Posts] WHERE EXISTS (SELECT [Id] FROM [Comments] WHERE [Comments].[PostId] = [Posts].[Id])", sqlServer.ToString());
+ }
+
  }
 }

QueryBuilder/Base.Where.cs

@@ -539,10 +539,6 @@ public Q WhereExists(Query query)
  throw new ArgumentException($"'{nameof(FromClause)}' cannot be empty if used inside a '{nameof(WhereExists)}' condition");
  }
 
- // remove unneeded components
- query = query.Clone().ClearComponent("select")
- .SelectRaw("1");
-
  return AddComponent("where", new ExistsCondition
  {
  Query = query,

QueryBuilder/Compilers/Compiler.Conditions.cs

@@ -247,7 +247,16 @@ protected virtual string CompileExistsCondition(SqlResult ctx, ExistsCondition i
  {
  var op = item.IsNot ? "NOT EXISTS" : "EXISTS";
 
- var subCtx = CompileSelectQuery(item.Query);
+
+ // remove unneeded components
+ var query = item.Query.Clone();
+
+ if (OmitSelectInsideExists)
+ {
+ query.ClearComponent("select").SelectRaw("1");
+ }
+
+ var subCtx = CompileSelectQuery(query);
 
  ctx.Bindings.AddRange(subCtx.Bindings);
 

QueryBuilder/Compilers/Compiler.cs

@@ -30,6 +30,12 @@ protected Compiler()
  /// <value></value> 
  public virtual bool SupportsFilterClause { get; set; } = false;
 
+ /// <summary>
+ /// If true the compiler will remove the SELECT clause for the query used inside WHERE EXISTS
+ /// </summary>
+ /// <value></value> 
+ public virtual bool OmitSelectInsideExists { get; set; } = true;
+
  protected virtual string SingleRowDummyTableName { get => null; }
 
  /// <summary>