unpaid monthly salaries (mysql +vb.net) - mysql

Question

I have a MySQL table some thing like that
NAME salary amount month 1 month 2 month 3 month 4
john 300 300 300 0 0
maria 400 400 0 0 0
tom 380 380 380 380 0
I wanna see results in table or list view or whatever like that
name unpaid month salary amount
john month 3 300
john month 4 300
maria month 2 400
maria month 3 400
maria month 4 400
tom month 4 380
I tried code like:
sql1="select name,month1 from table where month1=0 "
sql2="select name,month2 from table where month2=0"
sql3="select name,month3 from table where month3=0"
sql4="select name,month4 from table where month4=0"
Dim Sql = String.Concat(sql1, ";", sql2 ,";",sql2,";",sql4 )
but didn't work , any help pls ?

Answer 1

The syntax looks a little off in your code that you have now. I do not know if this is the exact code that you have in your program, but when the SQL statements are not properly formatted nothing will happen. I have made some changes to show what may be the issue.
sql1="SELECT name, month1, amount FROM table WHERE month1=0"
sql2="SELECT name, month2, amount FROM table WHERE month2=0"
sql3="SELECT name, month3, amount FROM table WHERE month3=0"
sql4="SELECT name, month4, amount FROM table WHERE month4=0"
Dim Sql = String.Concat(sql1, ";", sql2 ,";",sql2,";",sql4 )
The issue that I see with your current formatting is that you may want to have two separate tables for the name and the pay. With the separate tables you could then use foreign keys and join the two tables to have each name on every month with the amount they were paid that month. You would also be able to group the users based off of their name using GROUP BY
With the restructured table your call would be as simple as the statement below. Since I do not know your table names I have made fake ones for them.
Dim Sql = "SELECT NameTable.name, MonthTable.month, MonthTable.amount
FROM NameTable INNER JOIN MonthTable
ON {prmarykey for name} = {foreign key for month}
GROUP BY NameTable.name"
This should give you the result that you are looking for. Let me know if you have any questions or need clarification.

Answer 2

Try the UNION mysql aggregate :
sql1="select name,month1 as unpaid_month from table where month1=0 "
sql2="select name,month2 as unpaid_month from table where month2=0"
sql3="select name,month3 as unpaid_month from table where month3=0"
sql4="select name,month4 as unpaid_month from table where month4=0"
Dim Sql = String.Concat(sql1, " UNION ", sql2 ,"UNION ",sql2," UNION ",sql4

Answer 3

How you could use spaces before column names.
I would suggest you to use UNION.
But, here's the least version of SQL;
sql = "SELECT NAME, month1 as unpaid_month, salary_amount FROM tablename WHERE month1 = 0"
sql = sql & " UNION "
sql = sql & "SELECT NAME, month2 as unpaid_month, salary_amount FROM tablename WHERE month2 = 0"
sql = sql & " UNION "
sql = sql & "SELECT NAME, month3 as unpaid_month, salary_amount FROM tablename WHERE month3 = 0"
sql = sql & " UNION "
sql = sql & "SELECT NAME, month4 as unpaid_month, salary_amount FROM tablename WHERE month4 = 0"
But, the query is not good enough. What will happen if someone is paid half of its salary. And why you should get more than one record for a single person? Shouldn't there be any SUM for salary_amount and string concatenation for unpaid_month?
As it wasn't the part of your question, I can't post the advanced SQL here. Please ask for it in comment if you want that.
Please read these functions SUM() and GROUP_CONCAT() with temporary table AS TABLE. I think that you should use them for good programming.