Duplicate Columns With Inner Join

SELECT dealing_record.* ,shares.* ,transaction_type.* FROM shares INNER JOIN shares ON shares.share_ID = dealing_record.share_id INNER JOIN transaction_t

Solution 1:

You have duplicate columns, because, you're asking to the SQL engine for columns that they will show you the same data (with SELECT dealing_record.* and so on) , and then duplicates.

For example, the transaction_type.transaction_type_id column and the dealing_record.transaction_type_id column will have matching rows (otherwise you won't see anything with an INNER JOIN) and you will see those duplicates.

If you want to avoid this problem or, at least, to reduce the risk of having duplicates in your results, improve your query, using only the columns you really need, as @ConradFrix already said. An example would be this:

SELECT 
    dealing_record.Name
    ,shares.ID
    ,shares.Name
    ,transaction_type.Name
    ,transaction_type.ID
FROM 
    shares 
    INNERJOIN shares ON shares.share_ID = dealing_record.share_id
    INNERJOIN transaction_type ON transaction_type.transaction_type_id = dealing_record.transaction_type_id;

Solution 2:

Try to join shares with dealing_record, not shares again:

select dealing_record.*,
       shares.*,
       transaction_type.*FROM shares innerjoin dealing_record on shares.share_ID = dealing_record.share_id
            innerjoin transaction_type on transaction_type.transaction_type_id=
dealing_record.transaction_type_id;