I have a Microsoft Access 2010 form with dropboxes and a checkbox which represent certain parameters. I need to run a query with conditions based on these parameters. It should also be a possibility for no criteria from the dropdown boxes and checkbox in order to pull all data.
I have two working ways of implementing this:
I build a query with IIf statements in the WHERE clause, nesting statements until I have accounted for every combination of criteria. I reference the criteria in the SQL logic by using Forms!frmMyFrm!checkbox1 for example or by using a function FormFieldValue(formName,fieldName) which returns the value of a control with the input of the form and control name (This is because of previous issues). I set this query to run with the press of the form's button.
I set a vba sub to run with the press of the button. I check the conditions and set the query SQL to a predetermined SQL string based on the control criteria (referenced in the same way as the previous method). This also involves many If...Else statements, but is a little easier to read than a giant query.
What is the preferred method? Which is more efficient?
I don't believe you would find one way is more efficient over the other, at least not noticeably. For the most part it is simply personal preference.
I generally use VBA and check the value of each dropdown/checkbox and build pieces of the SQL query then put together at the end. The issue that you may run into with this method though is that if you have a large number of dropdowns and checkboxes the code is easy to get "lost" in.
If time to run is very key though you could always use some of the tips How do you test running time of VBA code? to see which way is faster.
After a lot of experimentation, and a bit of new information indicating having a pre-built query is faster than having SQL compiled in VBA, the most efficient and clear solution in the context of Microsoft Access is to build and save a number of dependent queries beforehand.
Essentially, build a string of queries each with an IIf dependent on a different criterium. Then you only need to run the final query. The only case where you would have to incorporate a VBA If...Else is if you need to query something more complicated than SELECT...WHERE(IIf(...)).
This has a few advantages:
The SQL is already compiled in the saved query, speeding things up.
No more getting lost in code:
There is no giant, nearly-impossible-to-edit query with way too many IIfs.
The minimal VBA code is even easier to follow.
At least for me, who's not an expert in SQL, it's convenient that I can often use the MS Access visual query builder for each part.
Related
My question right now is whether something can be done or not, as a result, no code has been included in this question. If it can be done what is the correct phrase that I can query and research this further.
I am working with a customer database where the request has been made that if a specific word is used in the comments field, that word is replaced or hidden when the query is used report and viewed using SSRS / Report Builder.
I had also wondered if even an expression can be written to hide or mask that word, and this would then be used in the tablix field that is used on the report.
Any suggestions are appreciated.
The database is Microsoft SQL 2016 with SSRS 2017 and Report Builder 2016.
If there is a specific word, then the answer is simple. You can just use replace(). In fact, you can add this into the table:
alter table t add safe_comments as (replace(comments, '<bad word>', 'XXXXXXX'));
You can extend this to a handful of hard-coded words by nesting replace() values.
I suspect, however, that your problem is that you have a fairly long list of words that you want to replace. If that is the case, such a simple solution is not going to work.
It is possible in SQL Server to remove a list of words, stored in a table, from a given comment. That requires a recursive CTE (or a user-defined function). This probably has acceptable performance for returning a single record or a handful of records. However, for scanning the entire table, it would probably be too slow.
The situation:
When I try to make a function or stored-proc, I usually start with a plain query window with sql-code. Often, I use #tblvar local tables to hold subsets of data needed later in the script.
During my testing of the developing script, I "select" the contents of the #tblvar-tables to observe the data to make sure it is correct for the scenario being tested.
Then, when I have debugged the complex query I then place that working code into a new stored-proc or user-defined-function.
But first, I need to "remove" or "comment-out" those "select #tblvar-tables" sentences.
I do this using the following sample/example code:
--DEBUG_SELECT
SELECT '#tblvarCostsAll_1' AS 'QueryName', * FROM #tblvarCostsAll WHERE (UID_VEHICLE IN (1628,1638,1672)) ORDER BY DATE_RANGE_CODE, UID_VGROUP, UID_VEHICLE;
--DEBUG_RETURN RETURN;
It becomes simple for me to "search/find" the phrase "--DEBUG_" and adjust the commenting process by joining the separate --DEBUG_SELECT-line with the adjacent SELECT-line.
The Question...
Is there a best practice in how to develop good SQL code from queries to udf-functions and usp-stored-procs?
Thanks...John
I frequently do a static analysis of SQL databases, during which I have the luxury of nobody being able to change the data except me.
However, I have not found a way to 'tell' this to SQL in order to prevent running the same query multiple times.
Here is what I would like to do, first I start with a complicated query that has a very small output.
SELECT * FROM MYTABLE WHERE MYPROPERTY = 1234
Then I run a simple query from the same window (Mostly using SQL server studio if that is relevant)
SELECT 1
Now I suddenly realize that I forgot to save the results from my first complicated (slow) query.
As I know the underlying data did not change (or even if it did) I would like to look one step back and simply get the result. However at the moment I don't know any trick to do this and I have to run the entire query again.
So the question summary is: How can I (automatically store/)get the results from recently executed queries.
I am particulary interested in simple select queries, and would be happy to allocate say 100MB memory for automated result storage. Would prefer a solution that works in SQL server studio with T-SQL, but other SQL solutions are also welcome.
EDIT: I am not looking for a way to manually prevent this from happening. In the cases where I can anticipate the problem it will not happen.
This can't be done in Microsoft SQL Server. SQL Server does not cache results, instead it caches data pages that were accessed by your query. This should make your query go a lot faster the second time around so it won't be as painful to re-run it.
In other databases, such as Oracle and MySQL, they do have a query caching mechanism that will allow you to retrieve the results directly the second time around.
I run into this frequently, I often just throw the results of longer-running queries into a temp table:
SELECT *
INTO #results1
FROM MYTABLE WHERE MYPROPERTY = 1234
SELECT *
FROM #results1
If the query is very long-running I might use a 'real' table. It's a good way to save on re-run time.
Downside is that it adds to your query.
You can also send query results to a file in SSMS, info on formatting the output is here: SSMS Results to File
The easiest way to do this is to run each query in its own SSMS window, the results will stay there until you close it, or run out of memory - besides that, I am not sure there is a way to accomplish what you want.
Once you close the SSMS window, I don't believe there is a way to get back 'cached' results.
This isn't a technical answer to your question. Having written queries and looking at results for many years, I am in the habit of saving the results in Excel, regardless of the database/query tool I'm using.
The format in Excel is rather methodical:
Each worksheet has the date. (Called something like "1 Jul".)
Each spreadsheet contains one month. (Typically with the month name like "work-201307".)
In the "B" column I copy and paste the query.
Underneath, in the "C" column, I copy and paste the results.
The next query starts a few lines after, one after the other.
I put the queries in the "B" column, so I can go to the "A" column and use to get to the first row. I put the results in the "C" column, so I can go to the "B" column and use to move between queries.
I mostly do this so I can go back and see the work I did many months ago. For instance, someone sends an email from February and says "do this again". I can go back to the February spreadsheet, go to the day it was created, and see what I was doing at that time.
In your question, though, I realize that I now instinctively solve this problem, because the "right click on the grid, copy with column headers, alt-tab to excel, alt-V" is a behavior that I comes quite naturally.
I was going to suggest you to run each query into a script with a counter (stored in a table) increased each time the query is executed (i.e. i++) and storing each query in a Temp Table called "tmpTable" + i, but it sounds very complicated to manage. Am I right?
Then I googled and I've found this Tool Pack: I didn't try it but you could take a look:
http://www.ssmstoolspack.com/Features
Hope it helps.
EDIT: added the folliwing link. There's the option to output as XML file and they mention SQL Server Integration Services as a possible solution too.
http://michaeljswart.com/2012/03/sending-query-results-to-others/#method5
SECOND EDIT: There's this DBMS-Independent tool too, it sounds interesting:
http://www.sql-workbench.net/
i am not sure this is what you want. Anyway check my answer
In sql server management studio you can open multiple tabs for executing queries. Open new tab for each query, then the result of executed queries will be available under that tab.
After executing one query in a tab dont use that tab for new query, open new tab for that job.
Have you considered using some kind of offline SQL client such as Excel? Specifically, Excel will retrieve the results into the spread sheet (using the Data ribbon/menus) where they are stored pretty much permanently as results. It will prompt you to refresh when necessary or you can do it on demand.
Your question as to whether it can be done in T/SQL or other databases depends on the database and results cache and even then they are options that the query processor can use not guarantees to the individual query.
I am very new to VBA and SQL and am trying to learn. I have a MS Access project that requires a VBA script that prompts the user to input two table names and numerous field names and create a SQL query utilizing those the names.
The specific SQL query I'm trying to use is below.
SELECT
A.user_index, A.input1, B.input1, A.input2, B.input2, A.input3, B.input3, B.input4,
A.input4, A.input5, B.input5
FROM
table1 AS A
LEFT JOIN
table2 AS B ON A.user_index = B.user_index
WHERE
(((A.input1) <> [B].[input1)) OR
(((A.input2) <> [B].[input2])) or
(((A.input4) <> [B].[input4]));
The overall purpose of this is to have a script that will be able to list fields for comparison that is applicable with any database. I know this is probably a relatively easy solution. However, I have no idea where to start.
My first instinct is to say "What have you tried so far?", but as you said, you don't know where to start.
It sounds like you need to first prompt the user for several field and table names, then build a query based on those values. I recommend first outlining exactly what you want your script to do. Maybe something like:
Declare variables to hold the values.
Prompt the user for each of the values and store them in the variables.
2a. After the user enters a value, make sure it is valid. If not, do something accordingly.
Declare a variable to hold your SQL query.
Construct the query.
Run the query.
This is obviously just an example. Break down each step into "baby steps" as much as possible.
It's a good idea to ask yourself how unique these baby steps are to your particular situation (hint: they almost certainly are not unique). If they aren't, then they have probably been solved tens of thousands of times already, so you have a very good chance of googling your questions.
If you still can't find an answer to how to do a particular step, feel free to ask here. Just remember to include your code even if it is broken :)
I am changing the command text for a data set inside the .rdl ffile:
I would like to know how can I update the resulting fields that are returned by the select statement:
I know that these fields must be automatically generated, so I was wondering if it's possible to update them right after editing the SQL code inline??
Usually when someone wants to have a look at the data in command text they are wanting it for reference to an end user(from what I have seen). You may want to amend it but ultimately with reporting your first goal should be: "What am I doing this for?" If your goal is dynamic creation at runtime then I would avoid this and offer a few other suggestions:
Procertize it. Making a stored procedure if you have the know how in SQL Server is a convenient and fast way to get what you want and you can optimize it if you know what you are doing with your SQL FU to get good results. The downside would be if you work with multiple environments you have to deploy your code for the TSQL as well as the RDL file.
Use an expression to build the dataset at runtime. In cases where I have been told that the query itself was not properly optimized by other developers they have mentioned doing this. I myself do not always see the advantage of doing this versus just having your predicate construction work well with good indexing on the source engine. Regardless you can build your dataset at runtime. It would be similar to hitting 'fx' next to the text and then putting in something like this(assuming you have a variable named #Start):
="Select thing
from table
Where >= " & Parameters!Start.Value
Again I have not really seen if this is really that much faster than:
Select thing
from table
Where >= #Start
But it is there if you just want to build it dynamically.
You can try to build your expression dynamically from parameters being PART of the select statement. SSRS is all about the 'expressions' and what you can do with them. Once you jump in and learn how they apply to everything you can go nuts so to speak on using them. A general rule though is the more of them you use and rely on the slower your reports will become.
I hope some of this may help, I would ask first is something dynamic due to a need to be event driven or is performance related.