Databases
StackOverflow2013
Postsdbo
POProperly using the Count Function
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POProperly using the Count Function
    primarykey
    data
    text
    <p>In the Enrollment_Changes table, the phone model listed is the phone the subscriber changed FROM on that date.</p> <p>If there is no subsequent change on Enrollment_Changes, the phone the subscriber changed TO is listed on the P_Enrollment table</p> <p>For example, subscriber 12345678 enrolled on 1/5/2011 with a RAZR. On 11/1/2011 he changed FROM the RAZR. You can see what he changed TO with the next transaction on Enrollment_Changes on 05/19/2012. </p> <p>How would you find the Count of subs that first enrolled with the iPhone 3? </p> <p>Here is the code I have for creating the tables</p> <p>Create Tables: TBL 1</p> <pre><code>USE [Test2] GO /****** Object: Table [dbo].[P_ENROLLMENT] ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[P_ENROLLMENT]( [Subid ] [float] NULL, [Enrollment_Date] [datetime] NULL, [Channel] [nvarchar](255) NULL, [Region] [nvarchar](255) NULL, [Active_Status] [float] NULL, [Drop_Date] [datetime] NULL, [Phone_Model] [nvarchar](255) NULL ) ON [PRIMARY] GO </code></pre> <p>TBL 2</p> <pre><code>USE [Test2] GO /****** Object: Table [dbo].[ENROLLMENT_CHANGES] ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[ENROLLMENT_CHANGES]( [Subid] [float] NULL, [Cdate] [datetime] NULL, [Phone_Model] [nvarchar](255) NULL ) ON [PRIMARY] GO </code></pre> <p>Insert TBL1</p> <pre><code>INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12345678, '2011-01-05 00:00:00', 'Retail', 'Southeast', 1, NULL, 'iPhone 4'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12346178, '2011-03-13 00:00:00', 'Indirect Dealers', 'West', 1, NULL, 'HTC Hero'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12346679, '2011-05-19 00:00:00', 'Indirect Dealers', 'Southeast', 0, '2012-03-15 00:00:00', 'Droid 2'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12347190, '2011-07-25 00:00:00', 'Retail', 'Northeast', 0, '2012-05-21 00:00:00', 'iPhone 4'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12347701, '2011-08-14 00:00:00', 'Indirect Dealers', 'West', 1, NULL, 'HTC Hero'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12348212, '2011-09-30 00:00:00', 'Retail', 'West', 1, NULL, 'Droid 2'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12348723, '2011-10-20 00:00:00', 'Retail', 'Southeast', 1, NULL, 'Southeast'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12349234, '2012-01-06 00:00:00', 'Indirect Dealers', 'West', 0, '2012-02-14 00:00:00', 'West'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12349745, '2012-01-26 00:00:00', 'Retail', 'Northeast', 0, '2012-04-15 00:00:00', 'HTC Hero'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12350256, '2012-02-11 00:00:00', 'Retail', 'Southeast', 1, NULL, 'iPhone 4'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12350767, '2012-03-02 00:00:00', 'Indirect Dealers', 'West', 1, NULL, 'Sidekick'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12351278, '2012-04-18 00:00:00', 'Retail', 'Midwest', 1, NULL, 'iPhone 3'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12351789, '2012-05-08 00:00:00', 'Indirect Dealers', 'West', 0, '2012-07-04 00:00:00', 'iPhone 3'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12352300, '2012-06-24 00:00:00', 'Retail', 'Midwest', 1, NULL, 'Droid 2'); INSERT INTO [P_ENROLLMENT]([Subid ], [Enrollment_Date], [Channel], [Region], [Active_Status], [Drop_Date], [Phone_Model]) VALUES(12352811, '2012-06-25 00:00:00', 'Retail', 'Southeast', 1, NULL, 'Sidekick'); </code></pre> <p>Insert TBL2</p> <pre><code>INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12345678, '2011-11-01 00:00:00', 'RAZR'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12346178, '2012-01-07 00:00:00', 'HTC Hero'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12348723, '2012-01-28 00:00:00', 'RAZR'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12350256, '2012-02-21 00:00:00', 'Blackberry Bold'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12349745, '2012-05-05 00:00:00', 'HTC Hero'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12345678, '2012-05-19 00:00:00', 'Palm Pre'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12347190, '2012-05-20 00:00:00', 'HTC Hero'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12350256, '2012-05-21 00:00:00', 'Blackberry Bold'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12349234, '2012-06-04 00:00:00', 'Palm Pre'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12346178, '2012-06-05 00:00:00', 'iPhone 3'); INSERT INTO [ENROLLMENT_CHANGES]([Subid], [Cdate], [Phone_Model]) VALUES(12350767, '2012-06-10 00:00:00', 'iPhone 3'); </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USKeyboardFriendly
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POProperly using the Count Function
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POProperly using the Count Function
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POProperly using the Count Function
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIf I understand the problem correctly, and I'm not sure I do, I think that the first model is in p_enrollment if there are no entries in enrollment_changes, otherwise it's in the first entry of enrollment_changes. Is that right?
      singulars
      1. POProperly using the Count Function
      1. USGilM
    2. COGreat job on your first SO question, including ALL the DDL. I would give you 5 stars if I could.
      singulars
      1. POProperly using the Count Function
      1. USRichardTheKiwi
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload