office 365 applications diagram inner outer loop

Well, there is, and it follows the same basic technique I described earlier. You could try to aggregate those results to return 1 row per Employee, and figure out how to pull just the billing rate that you need with a MAX(CASE …) expression or something similar, but now you are really over-complicating things. This means that you will get duplicated data with different rates in your result set. For employee rows that match a specific EmpType/Dept billing rate, it will still also return another row for the default rate since the second part of the OR expression still holds. However, it is not only inefficient, but it doesn't work. In this case, that is valid SQL and it will compile and execute. (B.EmpType = E.EmpType and B.Department = 'DEFAULT')) With each possibility JOIN'ed separately, you can now use a CASE expression in your SELECT clause to return data from the join that you need based on conditions or the join results.įor example, if you need to join Employees to either Stores or Offices depending on where they work, many SQL beginners think that a CASE will somehow let them get the results they need:īillRates B on ((B.EmpType = E.EmpType and B.Department = E.Department) OR

Instead of trying to alter a single INNER JOIN's relation from row to row, instead use multiple LEFT OUTER JOINS in your SELECT, one for each table or condition that you need to consider. There's a much better way to approach the problem. Often, you might encounter syntax errors, performance problems, or results not being returned the way you expect when trying this. You might think to do this with either a CASE expression or with some OR boolean logic in your JOIN expression. For example, some rows join to table A, others to table B.

Sometimes, when writing SELECTs, we come across situations in which we we need to write a join containing a condition of some sort, so that the join processed will vary for each row depending on the data.

Office 365 applications diagram inner outer loop