how to fetch data from multiple mysql tables with common composite primary key
Question
I have 15 tables with different column counts in mysql. Column count ranges from 225 to 250. I am importing data from 15 different CSV files on a daily basis.
All the tables have 19 common columns with the same values for particular day and a combination of 3 common columns can act as primary key.
I need to fetch the data from 15 tables without duplication to display it as a report. How to do this?
For the reference sample table structure is below:
<html>
<table cellpadding="0" cellspacing="auto" border="1" class="display" id="example" width="100%">
<thead>
<tr>
<th>Start time </th>
<th>End time </th>
<th>Query Granularity</th>
<th>RNC ID</th>
<th>Cell</th>
<th>Cellname</th>
<th>Access Success Rate Signalling (%)</th>
<th>Access Success Rate Speech (%)</th>
<th>Access Success Rate PS (%)</th>
<th>Access Success Rate HS (%)</th>
<th>Call Drop Rate Speech (%)</th>
<th>Call Drop Rate PS (%)</th>
<th>Call Drop Rate HS (%)</th>
<th>HOSR Speech (%)</th>
<th>iRAT HOSR out Speech (%)</th>
<th>iRAT HOSR out PS R99 (%)</th>
<th>number of rab establishment success for speech</th>
<th>number of rab establishment success for PS</th>
<th>number of rab establishment success for HS </th>
<th>number of CS call drop </th>
</tr>
</thead>
<tbody>
</table>
</html>
1 answers
solution1
1 ACCPTED 2012-10-22 14:31:29
As has been mentioned you'll need to have a common column count to make UNION query. To remove the duplicates surround the UNION statement with a SELECT DISTINCT <columna columnb > statement.
select distinct columna columnb from
(
select subcol0a columna, subcol0b columnb, '', '' from table0
union
select subcol1a columna, subcol1b columnb, '', '' from table1
) as query0
where <some condition>
Just alias the individual columns in the subquery so they match up when collected in the outer SELECT.
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