I apologize if this is an easy one, but I can't find this on the web anywhere!
I have a list of tables and queries, and a full list of fields from each table and query.
I want to choose my fields in an Access form, and then, on another form, choose a query/table in one column (along with a field) and join it to a table/query in another column (along with the field.) My form for the joins would look like this:
Object1 Field1 Object2 Field2
and so on. I would want to be able to choose my fields through combo boxes, THEN make the SQL string dynamically. I can't use a where clause -- it has to be a join.
The problem is, the structure will change every time. Access gets funny about putting in parentheses. Also, if an object is chosen more than once, Access will want to join it (assuming I do it right) in a different manner than T-SQL.
Is there a way to write a query in T-SQL, and quickly convert to Access? Does anyone know the FROM clause algorithm Access uses to construct the FROM clause? I am stuck here, and I cannot find a solution to save my soul! Thank you in advance, David
Related
Fist, let me say I know very little about SQL language and am trying to learn (albeit very slowly). I have created a database table with columns for
ECOREGION_ID
ECOREGION_NAME
SPECIES_NAME
CLASS
so that there is one row for each species name in each ecoregion. My end goal is to create a form in which I can enter in multiple species names and search for the ecoregions they share. For example, if I enter into the 4 different search boxes "Tiger", "Red Panda", "Sloth Bear", and "Rhino" it would bring up a list of all the Ecoregions in which these four species share. I am wondering a few things:
Is my data set up in the correct way in order to do this or is there a more efficient way to set i t up?
What statement should I use to create an sql statement to perform the search I want?
What is the technical term for what I am wanting to do? I have tried many different searches on different forums and can't seem to find what I am looking for, mostly because I probably don't know what to search, lol.
Thanks,
-Drew
You have ECORegion_ID and ECORegion_Name in the same table. I would suggest create a separate table to hold ECORegions. This table would have both an ID and Name. The search table would then only have the ECORegion_ID. This process is called normalization. It basically reduces redundant data in your database.
You are looking for a SELECT statement, which is used to pull data out of one or more tables. The statement has a WHERE option to restrict which rows you bring back and an IN expression as part of the WHERE to allow you to look for multiple keywords.
Search for Normalization to see why to put region name in a separate table. Look up SQL Select to get syntax for the select statement you should get off to a good start
Background
I have two tables:
Projects
EmployeeID
Employee
EmployeeID
Name
I have a query I am basing a form on containing, among other items:
SELECT e.Name FROM Projects p JOIN Employee e ON e.EmployeeID=p.EmployeeID
When I make a form in Access based on this query, I can very easily display e.Name on my form because it is joined from the query.
My real example is of course considerably more complicated than this simple example. The above works fine for read-only queries and scales well. However I would like to use a Splitform view and this becomes very slow with many joins for even small numbers of recordsets. Considering a large percentage of my joins are simple like the above, I am hoping for a way to remove as many as possible.
On the form, e.Name will be read only and not be update-able.
Similar question
In this question I am able to successfully change a combo-box into a lookup. The accepted answer allows a combo box to control Projects.EmployeeID by displaying Employee.Name field in the combo box.
Possible work-arounds
I know one way I could do this is use a combo-box but disable it. This would look a bit weird since it'd have the drop down selector but not be selectable.
Alternatively, I could make it a completely unbound field and write VBA code to update the form each time the recordset changes by running quick queries, getting the text value I am searching for, and updating a label accordingly.
Neither of these are overly appealing, however.
Question
How can I display a single text field on an Access split-form which is the result of a very simple query lookup, based on an ID from the main table field?
You can use Dlookup to return this reference very simply
Construct a Dlookup formula like:
=DLookUp("Name", "Employee", "EmployeeID =" & "[EmployeeID]"
and use this as the ControlSource for the textbox.
Some notes:
The & is important as it binds the formula to the single record displayed on the form
[EmployeeID] refers to the current record displayed on the form. This assumes that "EmployeeID" is included in the query for the form, whether bound to the Projects table or included in the query
I have problems with my records within my database, so I have a template with about 260,000 records and for each record they have 3 identification columns to determine what time period the record is from and location: one for year, one for month, and one for region. Then the information for identifying the specific item is TagName, and Description. The Problem I am having is when someone entered data into this database they entered different description for the same device, I know this because the tag name is the same. Can I write code that will go through the data base find the items with the same tag name and use one of the descriptions to replace the ones that are different to have a more uniform database. Also some devices do not have tag names so we would want to avoid the "" Case.
Also moving forward into the future I have added more columns to the database to allow for more information to be retrieved, is there a way that I can back fill the data to older records once I know that they have the same tag name and Description once the database is cleaned up? Thanks in advance for the information it is much appreciated.
I assume that this will have to be done with VBA of some sort to modify records by looking for the first record with that description and using a variable to assign that description to all the other items with the same tag name? I just am not sure of the correct VBA syntax to go about this. I assume a similar method would be used for the backfilling process?
Your question is rather broad and multifaceted, so I'll answer key parts in steps:
The Problem I am having is when someone entered data into this
database they entered different description for the same device, I
know this because the tag name is the same.
While you could fix up those inconsistencies easily enough with a bit of SQL code, it would be better to avoid those inconsistencies being possible in the first place:
Create a new table, let's call it 'Tags', with TagName and TagDescription fields, and with TagName set as the primary key. Ensure both fields have their Required setting to True and Allow Zero Length to False.
Populate this new table with all possible tags - you can do this with a one-off 'append query' in Access jargon (INSERT INTO statement in SQL).
Delete the tag description column from the main table.
Go into the Relationships view and add a one-to-many relation between the two tables, linking the TagName field in the main table to the TagName field in the Tags table.
As required, create a query that aggregates data from the two tables.
Also some devices do not have tag names so we would want to avoid the
"" Case.
In Access, the concept of an empty string ("") is different from the concept of a true blank or 'null'. As such, it would be a good idea to replace all empty strings (if there are any) with nulls -
UPDATE MyTable SET TagName = Null WHERE TagName = '';
You can then set the TagName field's Allow Zero Length property to False in the table designer.
Also moving forward into the future I have added more columns to the
database to allow for more information to be retrieved
Think less in terms of more columns than more tables.
I assume that this will have to be done with VBA of some sort to modify records
Either VBA, SQL, or the Access query designers (which create SQL code behind the scenes). In terms of being able to crunch through data the quickest, SQL is best, though pure VBA (and in particular, using the DAO object library) can be easier to understand and follow.
This is with respect to search of a text in a table
Table_Name:
Details
Columns:
Fname,Mname,Lname,NName
This table contains nearly one lakh records
We are using Oracle forms for some querying option
The user input one name the form searches the table for the name and based on the name either(Fname/Mname/Lname/NName) in which column its is present further actions are proceeeded.
The search is taking a long time since we have huge amount of data present in the table.
I tried with Functional indexes for the table but t did not work its also taking more time
Later i tried with something like this
concatenated all the names into one name and put it into a cursor.
Using the cursor output i tried with Instring but it is hanging
I also tried with searching for building a dynamic cursor but it did not work.
My database is Oracle
Can u help me to out to find an effective solution or please help me if i have missed something.
Thanks
First of all, 1 lakh (100,000) records is not in itself a large table.
The problem I can see is the query appears to be doing an OR against the Fname/Mname/Lname/NName columns.
This means the query will be doing at least one full-table scan to obtain the results.
You may wish to use debug to obtain the query it is firing against the database and attempt to tune this at the SQL prompt using auto trace.
You may need to clarify if the search is also doing something like a LIKE against these columns rather than an EQUALS. As a LIKE will impact the query further and affect indexes.
Certainly the use of INSTR will disable indexes on your searched column.
It is not clear if what your block is based on ie. table, view, query, procedure
You may want to try using the hint on the block properties of the form FIRST_ROWS.
Like a lot of developers who are comfortable with SQL syntax I get frustrated when working with Access's query editor. I'm talking about the raw SQL Syntax view, obviously.
One of its many annoying properties is that upon saving it will discard my layout / formatting. When reopening the query all I see is a bunch of unformatted SQL.
However, if my syntax is long and/or complex enough I've noticed that Access will retain my formatting and layout and, oh joy, the query remains clear and readable. I'm looking at an example right now with a page of SQL containing couple of UNIONs all nicely laid out from a few days ago.
At what point does Access flip over to allowing the user to retain his own formatting? Is it length? Complexity? And is there maybe even a trivial structural edit (if trivial structural isn't an oxymoron) I can make to all my queries which will force Access to leave my layout in place?
There are certain things that Access' query editor is not able to display in design mode.
Queries with UNION are the only thing that come to my mind right now, but there are probably more.
In my experience, Access always changes the layout as long as it's able to display the query in design mode.
As soon as you put something in the query that Access can not display in design mode (like UNION), Access leaves your layout and formatting as it is.
I couldn't figure out why Access kept changing my format in a union query (but not for every query or table included).
I simply created another SELECT query based upon the Union query and corrected everything in design view. It's a lot easier.
When I created the SELET query based upon the UNION query, I included tables or queries that I used as lookup tables and had formatted a field to select the second column from a record in a lookup field that the ubion query had anoyingly converted back to the first field in the selected record (usually the ID No of the record).
For example, I might lookup the account name in a record in the cash disbursements table that should display "Office Supplies Exp" but the Union Query converts at least one of the queries or tables I have combined in the union query to the Account Number, the first record in the lookup table, which was originally hidden in the lookup field.
Just to add to Christian's answer, I've done some more testing and find that UNION and DDL queries are left alone by Access.
If we add Pass through queries to that list, then that would match the queries deemed SQL Specific on the menu:
So, those would seem to be the three special cases.
Before saving just type the word union before the ;.
After opening Access next time, remove the word union and start working. When you want to save, first type union again.