Class Schedule
21 Aug | intro
23 Aug | clients
28 Aug | servers
30 Aug | networks
04 Sep | basics lab
06 Sep | structural layer
11 Sep | presentational layer
18 Sep | working with layers
20 Sep | behavior layer
25 Sep | images & design
27 Sep | website lab
02 Oct | object layers
02 Oct | graphics
09 Oct | document markup lab
11 Oct | spreadsheets, formulas & functions
16 Oct | thoughts about data display
18 Oct | Fall Break
23 Oct | database tools
25 Oct | spreadsheets lab
30 Oct | relational databases
01 Nov | tables
06 Nov | relationships
08 Nov | input & output
13 Nov | SQL
15 Nov | complex queries |
05.06 |
next session
20 Nov | databases lab
22 Nov | Thanksgiving
27 Nov | presentation design
29 Nov | presentation delivery
04 Dec | presentation lab
13 Dec | 0800-1100 | final in class presentation
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You can build queries that merge data from several tables
and that mathematically manipulate the data in the resultant dynasets.
You can apply a function on one of your queried fields by grouping by that field
Having revealed the totals row, you can apply a function on the field you wish.
This allows you to, in this case, to sum the number of times a state name appears in the Grouped By list.
Or will it? Can you actually SUM text values?
No, you cannot and you will be told so with an error message. What do you really want to do to see how many times a state name appears?
Does this work? Will it show me the names of the states and the number of publishers associated with each state that are in the database?
What does the criteria on the Group By field mean?
What, indeed, is a "Null value"?
it is a field that has nothing in it
therefore, you wish to have a query return a field that is empty, you need to
add the criteria that the field is empty, or "Is Null"
when you ask for Null, you get fields that have nothing in them
Likewise,
when you ask for Is Not Null,
you get fields that do not have nothing in them,
or better said, fields that are not empty.
So if you want to see records that have empty fields of some kind, create a null value criteria in your query.
You can add calculations by using the Expression Builder and you can add an expression to an existing query or to a new one you are building. Place cursor in a vacant field in the QBE box and click on the Builder button to open the expression builder.
Build an expression by deciding what you want to do and where you can find the values you need.
Once you have built the expression, click OK and the expression will be added as a new field in the query. You may need to rename the expression in the QBE grid and you may need to alter the properties of the newly created field so that it will display as you need it to
in this example, we might want to ensure that our newly named expression will display as money and not as numbers
and then to test it, to see if it works
... noticing how the new name we used for the expression ends up as a caption in the query.
When you sort on multiple fields, Access bases the sort on the leftmost field and uses fields to its right as tie-breakers when values in the leftmost field are the same
you may need to change the order of fields in the design grid if you are sorting on multiple fields, because the sort order will match the field order
in an ascending sort,
a descending sort is useful for date fields so you can place the most recent records at the top of a list