linq to sql: join multiple columns from the same table
This is the only way I was able to get it to work (in c#). var qry = from t1 in table1 join t2 in table2 on new {t1.ID,t1.Country} equals new {t2.ID,t2.Country} …
join
Procedurally transform subquery into join
Converting a subquery into a JOIN can be pretty straightforward: IN clause FROM TABLE_X x WHERE x.col IN (SELECT y.col FROM TABLE_Y y) …can be converted to: FROM TABLE_X x JOIN TABLE_Y y ON y.col = x.col Your JOIN criteria is where you have direct comparison. EXISTS clause But there are complications when you look … Read more
sql query joins multiple tables – too slow (8 tables)
I had a similar problem with several lookup tables joining to a large table with all id fields indexed. To monitor the effect of the joins on query time execution, I ran my query several times (limiting to first 100 rows), adding a Join to an additional table each time. After joining 12 tables, there … Read more
MySQL Multiple Joins in one query?
You can simply add another join like this: SELECT dashboard_data.headline, dashboard_data.message, dashboard_messages.image_id, images.filename FROM dashboard_data INNER JOIN dashboard_messages ON dashboard_message_id = dashboard_messages.id INNER JOIN images ON dashboard_messages.image_id = images.image_id However be aware that, because it is an INNER JOIN, if you have a message without an image, the entire row will be skipped. If this … Read more
Is there a PowerShell equivalent of `paste` (i.e., horizontal file concatenation)? [duplicate]
A few months ago, I submitted a proposal for including a Join-Object cmdlet to the standard PowerShell equipment #14994. Besides complexer joins based on a related property, the idea is to also be able to do a side-by-side join (by omiting the -On parameter). Taken this Paste command in Linux as an example: $State=”Arunachal Pradesh”, … Read more
Removing duplicate rows (based on values from multiple columns) from SQL table
Sample SQL FIDDLE 1) Use CTE to get max ship code value record based on ARDivisionNo, CustomerNo for each Customers WITH cte AS ( SELECT*, row_number() OVER(PARTITION BY ARDivisionNo, CustomerNo ORDER BY ShipToCode desc) AS [rn] FROM t ) Select * from cte WHERE [rn] = 1 2) To Delete the record use Delete query … Read more
MySQL Join Multiple Rows as Columns
An INNER JOIN will suffice your needs. MySQL has no PIVOT function by you can still simulate it using CASE and MAX() function. SELECT a.ID, a.NAME, MAX(CASE WHEN b.Race_Number = 1 THEN b.Place ELSE NULL END) Race1, MAX(CASE WHEN b.Race_Number = 2 THEN b.Place ELSE NULL END) Race2, MAX(CASE WHEN b.Race_Number = 3 THEN b.Place … Read more
SQL select join: is it possible to prefix all columns as ‘prefix.*’?
It seems the answer to your question is no, however one hack you can use is to assign a dummy column to separate each new table. This works especially well if you’re looping through a result set for a list of columns in a scripting language such as Python or PHP. SELECT ” as table1_dummy, … Read more
Pandas: Join dataframe with condition
Try the following: # Transform data in first dataframe df1 = pd.DataFrame(data) # Save the data in another datframe df2 = pd.DataFrame(data) # Rename column names of second dataframe df2.rename(index=str, columns={‘Reader_ID1’: ‘Reader_ID1_x’, ‘SITE_ID1’: ‘SITE_ID1_x’, ‘EVENT_TS1’: ‘EVENT_TS1_x’}, inplace=True) # Merge the dataframes into another dataframe based on PERSONID and Badge_ID df3 = pd.merge(df1, df2, how=’outer’, on=[‘PERSONID’, … Read more