"Distinct" results in complex query

Question

I have the following query, which returns all merchants in the database who have transactions between two given dates.

SELECT distinct me.id, me.merchant_num, me.merchant_nm, count(1) as num_transactions
       ,CASE WHEN me.status = 'A' THEN 'Yes' ELSE 'No' END as production_mode
FROM merchant_t me
LEFT OUTER JOIN transaction_t tt
    ON tt.merchant_id = me.id 
    AND tt.transaction_dt BETWEEN '2020-04-01' and '2020-04-30'
WHERE me.status = 'T'
GROUP BY me.id, me.merchant_num, me.merchant_nm, me.status

But, there is additional information I need to include in the query. I've written the enhanced query below, but it results in duplicated merchants. I know the query could be written better, but that's the limit of my SQL knowledge.

I need to keep the same number of results as the above query.

SELECT distinct me.id, me.merchant_num, me.merchant_nm, count(1) as num_transactions
       ,CASE WHEN me.status = 'A' THEN 'Yes' ELSE 'No' END as production_mode   

       -- additional information needed as below, with comments

       -- the date of the last transaction that uses IBank (IBA)
       ,(select max(transaction_dt) 
           from transaction_t where merchant_id = me.id 
           and tt.bank_txt = 'IBA') as last_ibank_transaction

       -- the value of the "trans_live" column for the merchant's most recent transaction
       ,(select top 1 trans_live          
           from transaction_t
           where merchant_id = me.id order by transaction_dt desc) is_live
FROM merchant_t me
    LEFT OUTER JOIN transaction_t tt
         ON tt.merchant_id = me.id 
         AND tt.transaction_dt BETWEEN '2020-04-01' and '2020-04-30'
    WHERE me.status = 'T'
    GROUP BY me.id, me.merchant_num, me.merchant_nm, me.status, tt.bank_txt

This returns duplicated merchants. In the screenshot below, I have filtered on a single merchant to show the duplication. The first result set is from the original query. The second is from the updated query. "DISTINCT" does its job but I only want to see one merchant record.

enter image description here

There are two tables involved:

merchant_t
----------
id     merchant_num    merchant_nm    status


transaction_t
--------------
id     merchant_id     transaction_dt     trans_live     bank_txt

EDIT

I am trying to avoid having the dates inside a subquery

VARUN'S ANSWER

The updated query returns many duplicates as below.

MAX(CASE WHEN tt.bank_txt = 'IBA'

SQL SCRIPT

USE [XYZ]
GO
/****** Object:  Table [dbo].[merchant_t]    Script Date: 6/10/2020 5:23:51 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[merchant_t](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [merchant_num] [nvarchar](50) NULL,
    [merchant_nm] [nvarchar](100) NULL,
    [status] [nchar](1) NULL
) ON [PRIMARY]
GO
/****** Object:  Table [dbo].[transaction_t]    Script Date: 6/10/2020 5:23:51 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[transaction_t](
    [id] [int] IDENTITY(1,1) NOT NULL,
    [merchant_id] [int] NULL,
    [transaction_dt] [datetime] NULL,
    [trans_live] [bit] NULL,
    [bank_txt] [nvarchar](30) NULL
) ON [PRIMARY]
GO
SET IDENTITY_INSERT [dbo].[merchant_t] ON 
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (335, N'PriceBusterDVD_NZ_AN', N'Pricebuster NZ ANZ', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (341, N'T6400050', N'Merco Test Merchant', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (342, N'6400262', N'Musac School Test 1', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (366, N'T6400093', N'Paystation Limited Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (367, N'T6400435', N'PB Technologies Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (374, N'PriceBusterDVD_NZ_BN', N'Pricebuster NZ BNZ', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (389, N'TAirNewZealandNZ_All', N'Test Air NZ - All', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (390, N'T6400061', N'The Warehouse Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (392, N'T6400246', N'University of Waikato Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (538, N'T6400449', N'NZTA Payments Dev System Testing', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (544, N'T6400447', N'NZTA Tolling Dev System Testing', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (631, N'SS64000475', N'Smeedi Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (729, N'T6400048', N'Marram Community Trust Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (776, N'SS64000665', N'POLi Test Bench', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (936, N'T6400002', N'WorldRemit Test NZ', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1033, N'SS64005103', N'Ahura Consulting Limited', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1173, N'SS64005386', N'Warehouse Stationery Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1236, N'SS64005423', N'KlickEx Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1435, N'T6400477', N'NZMCA', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1580, N'T6400478', N'2 Degrees Mobile - Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1626, N'SS64006121', N'Property Council New Zealand', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1714, N'SS64006558', N'ServiceFinder.co.nz', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1972, N'T6400480', N'2 Degrees Mobile Accept Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (1988, N'T6400484', N'HelloClub Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2011, N'T6400482', N'Horowhenua District Council Test', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2260, N'SS64008067', N'Success Global', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2274, N'64007479', N'Samsung Electronics New Zealand', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2397, N'SS64008228', N'MyBitcoinSaver.com', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2418, N'6400478', N'Spark Staging', N'T')
GO
INSERT [dbo].[merchant_t] ([id], [merchant_num], [merchant_nm], [status]) VALUES (2441, N'SS64008239', N'Kiwi Petz', N'T')
GO
SET IDENTITY_INSERT [dbo].[merchant_t] OFF
GO
SET IDENTITY_INSERT [dbo].[transaction_t] ON 
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215957, 389, CAST(N'2020-04-01T06:55:37.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215958, 389, CAST(N'2020-04-01T06:56:13.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215959, 389, CAST(N'2020-04-01T07:06:47.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215960, 389, CAST(N'2020-04-01T07:09:09.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215961, 389, CAST(N'2020-04-01T08:19:28.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215962, 389, CAST(N'2020-04-01T08:19:45.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215963, 389, CAST(N'2020-04-01T08:19:57.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215964, 389, CAST(N'2020-04-01T08:20:16.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215965, 389, CAST(N'2020-04-01T09:33:40.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215966, 389, CAST(N'2020-04-01T09:33:46.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215967, 389, CAST(N'2020-04-01T11:05:35.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215968, 389, CAST(N'2020-04-01T11:06:13.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215969, 389, CAST(N'2020-04-01T11:12:51.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215970, 389, CAST(N'2020-04-01T11:17:38.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215971, 389, CAST(N'2020-04-01T12:45:13.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215972, 389, CAST(N'2020-04-01T12:45:49.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215973, 389, CAST(N'2020-04-01T12:50:17.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18201776, 1580, CAST(N'2020-04-01T14:16:38.000' AS DateTime), 0, N'ANZ')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215974, 389, CAST(N'2020-04-01T12:59:06.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215975, 389, CAST(N'2020-04-01T14:18:13.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215976, 389, CAST(N'2020-04-01T14:18:21.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215977, 389, CAST(N'2020-04-01T14:26:15.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215978, 389, CAST(N'2020-04-01T14:33:02.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215979, 389, CAST(N'2020-04-01T15:12:43.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215980, 389, CAST(N'2020-04-01T15:12:46.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215981, 389, CAST(N'2020-04-01T15:41:14.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18215982, 389, CAST(N'2020-04-01T15:43:53.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18223719, 2441, CAST(N'2020-04-02T10:20:03.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231457, 389, CAST(N'2020-04-02T07:11:32.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231458, 389, CAST(N'2020-04-02T07:13:06.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231459, 389, CAST(N'2020-04-02T08:49:33.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231460, 389, CAST(N'2020-04-02T09:03:17.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231461, 389, CAST(N'2020-04-02T09:08:39.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231462, 389, CAST(N'2020-04-02T11:17:25.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231463, 389, CAST(N'2020-04-02T11:20:53.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231464, 389, CAST(N'2020-04-02T11:22:38.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231465, 389, CAST(N'2020-04-02T12:03:20.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231466, 389, CAST(N'2020-04-02T12:03:58.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231467, 389, CAST(N'2020-04-02T12:20:27.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18231468, 389, CAST(N'2020-04-02T12:37:47.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18233881, 341, CAST(N'2020-04-02T13:54:30.000' AS DateTime), 0, N'ANZ')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18237848, 2011, CAST(N'2020-04-03T13:31:36.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245130, 389, CAST(N'2020-04-03T06:24:34.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245131, 389, CAST(N'2020-04-03T06:26:47.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245132, 389, CAST(N'2020-04-03T10:55:09.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245133, 389, CAST(N'2020-04-03T11:00:42.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245134, 389, CAST(N'2020-04-03T11:00:57.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245135, 389, CAST(N'2020-04-03T14:01:58.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245136, 389, CAST(N'2020-04-03T14:08:48.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245137, 389, CAST(N'2020-04-03T14:41:57.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18245138, 389, CAST(N'2020-04-03T14:44:40.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18250367, 2441, CAST(N'2020-04-04T09:53:19.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18274546, 2274, CAST(N'2020-04-06T02:50:01.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18274563, 1714, CAST(N'2020-04-06T06:36:45.000' AS DateTime), 1, N'ANZ')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277532, 389, CAST(N'2020-04-06T06:37:57.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277533, 389, CAST(N'2020-04-06T06:46:45.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277534, 389, CAST(N'2020-04-06T07:36:29.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277535, 389, CAST(N'2020-04-06T07:43:00.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277536, 389, CAST(N'2020-04-06T08:11:22.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277537, 389, CAST(N'2020-04-06T08:12:13.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18279767, 341, CAST(N'2020-04-06T09:40:12.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18268407, 1033, CAST(N'2020-04-06T20:15:56.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270264, 544, CAST(N'2020-04-06T12:36:12.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270265, 544, CAST(N'2020-04-06T12:37:11.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270266, 544, CAST(N'2020-04-06T12:38:08.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270267, 544, CAST(N'2020-04-06T12:40:05.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270268, 544, CAST(N'2020-04-06T12:42:50.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270269, 544, CAST(N'2020-04-06T12:43:36.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270270, 544, CAST(N'2020-04-06T12:45:09.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18270271, 544, CAST(N'2020-04-06T12:45:26.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18273055, 538, CAST(N'2020-04-06T12:34:02.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277538, 389, CAST(N'2020-04-06T11:30:42.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277539, 389, CAST(N'2020-04-06T11:31:06.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277540, 389, CAST(N'2020-04-06T11:44:56.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277541, 389, CAST(N'2020-04-06T11:49:43.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277542, 389, CAST(N'2020-04-06T13:07:37.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277543, 389, CAST(N'2020-04-06T13:08:50.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277544, 389, CAST(N'2020-04-06T14:10:14.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277545, 389, CAST(N'2020-04-06T14:10:37.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277546, 389, CAST(N'2020-04-06T14:10:54.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277547, 389, CAST(N'2020-04-06T14:14:26.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277548, 389, CAST(N'2020-04-06T15:25:39.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277549, 389, CAST(N'2020-04-06T15:26:02.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277550, 389, CAST(N'2020-04-06T18:31:10.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277551, 389, CAST(N'2020-04-06T18:33:05.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277552, 389, CAST(N'2020-04-06T18:44:58.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277553, 389, CAST(N'2020-04-06T19:46:52.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277554, 389, CAST(N'2020-04-06T20:31:33.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277555, 389, CAST(N'2020-04-06T20:43:56.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277556, 389, CAST(N'2020-04-06T20:51:42.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18277557, 389, CAST(N'2020-04-06T21:03:01.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18293723, 389, CAST(N'2020-04-07T06:20:15.000' AS DateTime), 0, N'IBA')
GO
INSERT [dbo].[transaction_t] ([id], [merchant_id], [transaction_dt], [trans_live], [bank_txt]) VALUES (18293724, 389, CAST(N'2020-04-07T06:45:17.000' AS DateTime), 0, N'IBA')
GO

LATEST VERSION RESULTS

enter image description here

INDEXES

merchant_t

/****** Object:  Index [PK_merchant_t]    Script Date: 6/13/2020 8:40:44 PM ******/
ALTER TABLE [dbo].[merchant_t] ADD  CONSTRAINT [PK_merchant_t] PRIMARY KEY CLUSTERED 
(
    [id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

/****** Object:  Index [IX_status]    Script Date: 6/13/2020 8:44:08 PM ******/
CREATE NONCLUSTERED INDEX [IX_status] ON [dbo].[merchant_t]
(
    [status] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

transaction_t

/****** Object:  Index [IX_merchant_id]    Script Date: 6/13/2020 8:48:08 PM ******/
CREATE NONCLUSTERED INDEX [IX_merchant_id] ON [dbo].[transaction_t]
(
    [merchant_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO


/****** Object:  Index [IX_transaction_dt]    Script Date: 6/13/2020 8:45:59 PM ******/
CREATE NONCLUSTERED INDEX [IX_transaction_dt] ON [dbo].[transaction_t]
(
    [transaction_dt] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

/****** Object:  Index [IX_trans_live]    Script Date: 6/13/2020 8:46:57 PM ******/
CREATE NONCLUSTERED INDEX [IX_trans_live] ON [dbo].[transaction_t]
(
    [trans_live] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

/****** Object:  Index [IX_merchant_id]    Script Date: 6/13/2020 8:47:17 PM ******/
CREATE NONCLUSTERED INDEX [IX_merchant_id] ON [dbo].[transaction_t]
(
    [merchant_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

/****** Object:  Index [IX_bank_txt]    Script Date: 6/13/2020 8:47:37 PM ******/
CREATE NONCLUSTERED INDEX [IX_bank_txt] ON [dbo].[transaction_t]
(
    [bank_txt] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

Vladimir Baranov · Accepted Answer

In your first query you have this clause:

GROUP BY me.id, me.merchant_num, me.merchant_nm, me.status

In your second query you have this clause:

GROUP BY me.id, me.merchant_num, me.merchant_nm, me.status, tt.bank_txt

You are getting different number of rows in the second query because your GROUP BY is different. You need to keep it the same.

Here is one way to do it. I used CTE to make the query readable.

As you can see in the comments in the query, it returns the value of the trans_live column for the merchant's most recent transaction. Most recent transaction of the merchant across all dates, regardless of the filter in the CTE. Same with the date of the last transaction that uses IBank (IBA). It returns the last transaction of the merchant across all dates, regardless of the filter in the CTE.

It is not clear from the question if this is what you want, though. Please clarify.

WITH
CTE_Merchants
AS
(
    SELECT -- distinct
        -- you don't need distinct here, because GROUP BY does it
        -- try to comment out distinct, you should get exactly the same result
        me.id, me.merchant_num, me.merchant_nm
        ,count(tt.id) as num_transactions
        -- return 0 count for merchants that don't have any transactions
        -- within the given range of dates

        ,CASE WHEN me.status = 'A' THEN 'Yes' ELSE 'No' END as production_mode
    FROM
        merchant_t me
        LEFT OUTER JOIN transaction_t tt
            ON  tt.merchant_id = me.id 
            AND tt.transaction_dt BETWEEN '2020-04-01' and '2020-04-30'
    WHERE me.status = 'T'
    GROUP BY me.id, me.merchant_num, me.merchant_nm, me.status
)
SELECT
    CTE_Merchants.id
    ,CTE_Merchants.merchant_num
    ,CTE_Merchants.merchant_nm
    ,CTE_Merchants.num_transactions
    ,CTE_Merchants.production_mode
    ,A1.is_live
    ,A2.last_IBA_transaction_dt
FROM
    CTE_Merchants
    OUTER APPLY
    (
        -- use OUTER APPLY (not CROSS APPLY) in case there are merchants with no transactions
        -- The value of the "trans_live" column for the merchant's most recent transaction.
        -- Most recent across all dates, regardless of the filter in the CTE
        select top 1
            transaction_t.trans_live AS is_live
        from transaction_t
        where
            transaction_t.merchant_id = CTE_Merchants.id
        order by transaction_dt desc
    ) AS A1
    OUTER APPLY
    (
        -- use OUTER APPLY (not CROSS APPLY) in case there are merchants with no transactions
        -- The date of the last transaction that uses IBank (IBA).
        -- The last transaction across all dates, regardless of the filter in the CTE
        select top 1
            transaction_t.transaction_dt AS last_IBA_transaction_dt
        from transaction_t
        where
            transaction_t.merchant_id = CTE_Merchants.id
            and transaction_t.bank_txt = 'IBA'
        order by transaction_dt desc
    ) AS A2
;

For this query to work efficiently, I would recommend to create certain indexes. You already have an index IX_status on the merchant_t table. This is good.

Those indexes that you have on the transaction_t table are not the best for this kind of query. You existing indexes IX_transaction_dt, IX_trans_live, IX_bank_txt are not useful for this query. Even IX_merchant_id by itself is not really useful, especially if you replace it with a composite index on (merchant_id, transaction_dt), as I've shown below.

I hope you do have a clustered primary key on id in transaction_t table. Similar to the primary key in the merchant_t table. If not, I'd create it.

Then, for efficient join between merchant_t and transaction_t tables and for efficient retrieval of the latest trans_live we need the following index:

CREATE NONCLUSTERED INDEX [IX_merchant_id_transaction_dt] ON [dbo].[transaction_t]
(
    merchant_id,
    transaction_dt -- you can put DESC here, but it should not matter
) INCLUDE (trans_live)

The order of columns in this index is important.

You have an index on just transaction_dt. This query might use it, but it would be not as efficient as on (merchant_id, transaction_dt). Your current index is useful if you have queries that filter by transaction date without looking at the merchant_id. If you don't have such queries, you'd better drop it. Having too many indexes "just in case" may be a problem for optimizer, and it slows down updates and inserts.

For efficient retrieval of the last last_IBA_transaction_dt we'll need this index:

CREATE NONCLUSTERED INDEX [IX_merchant_id_bank_txt_transaction_dt] ON [dbo].[transaction_t]
(
    merchant_id,
    bank_txt,
    transaction_dt -- you can put DESC here, but it should not matter
)

Again, the order of columns in this index is important.

If you don't want to create two indexes specifically for this query, you can try just one index, which is great for getting trans_live and should somewhat help with last_IBA_transaction_dt.

CREATE NONCLUSTERED INDEX [IX3] ON [dbo].[transaction_t]
(
    merchant_id,
    transaction_dt DESC
) INCLUDE (trans_live, bank_txt)

You can try and measure performance with the first two indexes and then just with the third one and compare.

By the way, if there are merchants that don't have any transactions within the given range of dates, then the query will return a row for these merchants. The COUNT in your original query will return 1 for these merchants. Probably this is not what you want.

To return 0 count for these merchants, the COUNT function should be COUNT(tt.id). I have made these changes in the code above.

dnoeth · Answer

This tries to get rid of the two Scalar Subqueries/Outer Apply. It runs a single aggregation on the transaction table using a conditional aggregate and the old piggyback trick to get the latest trans_live.

SELECT
   me.id
  ,me.merchant_num
  ,me.merchant_nm
   -- return 0 count for merchants that don't have any transactions
   -- within the given range of dates
  ,Count(CASE WHEN tt.transaction_dt BETWEEN '2020-04-01' AND '2020-04-30' THEN tt.id end) AS num_transactions
   -- the date of the last transaction that uses IBank (IBA)
  ,CASE WHEN me.status = 'A' THEN 'Yes' ELSE 'No' END AS production_mode   
  ,Max(CASE WHEN bank_txt = 'IBA' THEN tt.transaction_dt END) AS last_IBA_transaction_dt
      -- the value of the "trans_live" column for the merchant's most recent transaction
      -- piggybacks the trans_live on the max transaction_dt
      -- similar to FIRST_VALUE
     ,convert(bit, Substring(Max(convert(CHAR(8), tt.transaction_dt, 112) + convert(CHAR(1), trans_live)), 9, 1)) AS is_live
FROM merchant_t AS me
LEFT JOIN transaction_t AS tt
  ON tt.merchant_id = me.id 
WHERE me.status = 'T' 
GROUP BY 
   me.id
  ,me.merchant_num
  ,me.merchant_nm
  ,me.status

Don't ask me about adding indexes for improving performance, I don't work with SQL Server anymore and my main DBMS Teradata usually runs fast without adding indexes for specific queries :-)

"Distinct" results in complex query

Tags:

sql

sql-server

EDIT

VARUN'S ANSWER

SQL SCRIPT

LATEST VERSION RESULTS

INDEXES

merchant_t

transaction_t

user460114

Video Answer

2 Answers

Vladimir Baranov

dnoeth

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"Distinct" results in complex query

Tags:

sql

sql-server

EDIT

VARUN'S ANSWER

SQL SCRIPT

LATEST VERSION RESULTS

INDEXES

merchant_t

transaction_t

user460114

Video Answer

2 Answers

Vladimir Baranov

dnoeth

Related questions

Recent Activity

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