158
edits
Changes
Jump to navigation
Jump to search
→Finding Companies that Underwent IPOs and MAs
#Perform an INNER JOIN on the two tables in order to find the companies that underwent both MAs and IPOs. Do this by joining on the primary keys of portcos in both tables. Load this table into an excel sheet and manually find which companies you want to keep as MAs and which you want to keep as IPOs. Make sure to keep the portco primary key in this table.
#Load the decided IPO and MA data back into the database, including the primary keys of the portcos.
#LEFT JOIN the MA table with the IPO table. Join on primary keys of portcos. Select the companies where the IPO table are null as these are the companies that only had MAs. Do the same for IPOs. Now you have tables of companies that underwent only MAs and only IPOs.
#Join the companies that underwent IPOs only and the chosen IPOs back to the original key using the primary key of the company which must be in both tables. Repeat this for the MA table.
