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POCan I Group By an Unknown Number of Columns?
 

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  1. POCan I Group By an Unknown Number of Columns?
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    <p>I am currently trying to re-write a stored procedure to take into account the normalisation of one of our tables. In the original procedure we have two tables: </p> <pre><code>CREATE TABLE #t_batch (batch_id integer, thread_group NVARCHAR(60), dye_code_1 NVARCHAR(10), dye_conc_1 NUMERIC(19, 7), dye_code_2 NVARCHAR(10), dye_conc_2 NUMERIC(19, 7), dye_code_3 NVARCHAR(10), dye_conc_3 NUMERIC(19, 7), dye_code_4 NVARCHAR(10), dye_conc_4 NUMERIC(19, 7), dye_code_5 NVARCHAR(10), dye_conc_5 NUMERIC(19, 7), dye_code_6 NVARCHAR(10), dye_conc_6 NUMERIC(19, 7)) CREATE TABLE #t_group (group_id INTEGER IDENTITY(1, 1), dye_code_1 NVARCHAR(10), dye_conc_1 NUMERIC(19, 7), dye_code_2 NVARCHAR(10), dye_conc_2 NUMERIC(19, 7), dye_code_3 NVARCHAR(10), dye_conc_3 NUMERIC(19, 7), dye_code_4 NVARCHAR(10), dye_conc_4 NUMERIC(19, 7), dye_code_5 NVARCHAR(10), dye_conc_5 NUMERIC(19, 7), dye_code_6 NVARCHAR(10), dye_conc_6 NUMERIC(19, 7), thread_group NVARCHAR(60), num_batches INTEGER) </code></pre> <p>After a number of actions #t_batch was populated with a number of records. We then inserted data into #t_group in the following way:</p> <pre><code>INSERT INTO #t_group (dye_code_1, dye_conc_1, dye_code_2, dye_conc_2, dye_code_3, dye_conc_3, dye_code_4, dye_conc_4, dye_code_5, dye_conc_5, dye_code_6, dye_conc_6, thread_group, num_batches) SELECT dye_code_1, dye_conc_1, dye_code_2, dye_conc_2, dye_code_3, dye_conc_3, dye_code_4, dye_conc_4, dye_code_5, dye_conc_5, dye_code_6, dye_conc_6, thread_group, COUNT(batch_id_fk) FROM #t_batch GROUP BY dye_code_1, dye_conc_1, dye_code_2, dye_conc_2, dye_code_3, dye_conc_3, dye_code_4, dye_conc_4, dye_code_5, dye_conc_5, dye_code_6, dye_conc_6, thread_group ORDER BY dye_code_1, dye_conc_1, dye_code_2, dye_conc_2, dye_code_3, dye_conc_3, dye_code_4, dye_conc_4, dye_code_5, dye_conc_5, dye_code_6, dye_conc_6, thread_group </code></pre> <p>So, we had a series of records that are grouped by the dye columns and a unique group_id for each unique combination of dyes and their concentrations. Also, there is a count of the batch records for each group. </p> <p>However, since there is in reality no limit to the number of dyes for a batch the tables have been normalised:</p> <pre><code>CREATE TABLE #t_batch (batch_id INTEGER, thread_group NVARCHAR(60)) CREATE TABLE #t_batch_dye (batch_id_fk INTEGER, stage INTEGER, sequence INTEGER, dye_code NVARCHAR(10), dye_conc NUMERIC(19,7)) CREATE TABLE #t_group (group_id INTEGER IDENTITY(1, 1), thread_group NVARCHAR(60), num_batches INTEGER) CREATE TABLE #t_group_dye (group_id INTEGER, stage INTEGER, sequence INTEGER, dye_code NVARCHAR(10), dye_conc NUMERIC(19,7)) </code></pre> <p>Now, my question is: assuming that we have #t_batch and #t_batch_dye populated and that there are a varying number of #t_batch_dye records for each record in #t_batch, how can I insert records into #t_group with a unique group_id for each unique combination of dyes and their concentrations as well as a count of the batches for each group?</p> <p>Is this something I could use the PIVOT keyword for? The examples I have found on the web all seem to assume that the number of pivoted fields is known in advance.</p> <p>Many thanks, </p> <p>David</p> <p>Glasgow, Scotland</p> <hr> <p>Update:</p> <p>What I have done is to use a function that returns a concatenated string of codes and concs and used that to group the data.</p> <pre><code>DECLARE @dyes NVARCHAR(2000) SELECT @dyes = ISNULL(@dyes,'') + dye_code + ' ' + convert(nvarchar, requested_dye_conc) + ' ' FROM #t_batch_dye WHERE batch_id_fk = @batch_id ORDER BY dye_code ASC </code></pre>
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