How to find fields in a unknown table in a database? - database

Good morning!
I'm with the need to look in my database, one column of a table that does not know the name at first, what happens is the following:
In my application created for each project, a table is created which takes the name of this project, taking the given name and concatenating with the date and time of creation. So the name of this table is stored in another table called projects that have a field that tells the client that belongs to that project. When I do SELECT want to see the names of application projects related to the ID's of customers, browse the database tables behind those those customers and bring me these tables, so that we can finally see the desired fields.
Do not know if I could be clear, if they need more details just talk!
Thanks!

If I understood you correctly, you need to find the exact names of the tables that were named like your project plus they have some additional characters in their names (that look like dates and times).
Well, you can list all the tables that start with the name of your project, using a query like this:
SELECT *
FROM sys.tables
WHERE name LIKE 'yourprojectname%'
sys.tables is a system view where all your tables are listed.
'yourprojectname%' is a mask used for filtering through the list of tables. The % character is neccessary. It means 'any character or characters, any number of them (or none of them)'. (Without % the output would show you only one table whose name is exactly like your project's name. If such a table exists, that is.)

Related

Access database 2013 - Join three tables with list of data values in two of the tables

My main Access table contains 95 rows. One column is a name field with a unique name in each field. Two other tables also have a name column, but he name field from each of these tables contain one or more names separated by comma and a space. These tables are different lengths too, one has 99 rows the other has 33.
I need to link the data from these tables to a comprehensive form. To do this I think I want to make a cross tab query using the value in the Main table name field. It will need to search the name field of the other tables to see if one of the listed names match.
Please help.
Are You looking for this:
SELECT * FROM mainTable, Tble99Rows, Tbl33Rows
WHERE InStr(mainTable.Name, Tble99Rows.Name) AND InStr(mainTable.Name, Tble33Rows.Name)
?
Note it could be inaccurate, for example: it will link records with name Max and Maxine.
For proper Table Joining, Follow Data-Base normalization rules, in our case the First rule: all the attributes in a relation must have atomic domains. The values in an atomic domain are indivisible units.
EDIT:
Please read more: Is storing a delimited list in a database column really that bad?

SSRS parameters, populating the available fields list

When producing a list of available parameter properties, rather than manually typing each persons name in one by one, is there any way of just populating the data from the table/view which holds all the possible names?
I assume its in the circled box however all that does it let me point to a dataset and then field which I have tried selecting StaffName (being the field that is the one I'm using) if I then run the report it falls over.
Add a new dataset to the report, maybe called StaffMembersDS. The SQL for it might look like:
SELECT Id, Name
FROM StaffMember;
Then assign Name to Label and Id to Value.
BTW if this is related to your last question you're going to run into the trouble that when a user picks a staff member name from the drop down list they are picking only one value. So for your case you might want the Value field to be tied to Name as well as the label. That would allow you to use the query in your last question - SSRS Parameters - which collects related Id values.
SSRS's concept of a query is largely tied to a data set that you define in Report Data.
When you choose 'Use a query', you should be choosing a pre-defined query from Report Data. Of course, the good news is that you can define these yourself.
So let's take your example. You want your possible parameter options to be StaffNames.
Create a new dataset in Report Data. It should return all possible staff names for your report.
Something like:-
SELECT DISTINCT
StaffName,
StaffID
FROM
MyReportViewOrTable
Once you have defined this dataset, you should be able to use it as a source of parameter values.

Full-text Search on Joined, Hierarchical Records in SQL Server 2008

Probably a noob question, but I'll go for it nevertheless.
For sake of example, I have a Person table, a Tag table and a ContactMethod table. A Person will have multiple Tag records and multiple ContactMethod records associated with them.
I'd like to have a forgiving search which will search among several fields from each table. So I can find a person by their email (via ContactMethod), their name (via Person) or a tag assigned to them.
As a complete noob to FTS, two approaches come to mind:
Build some complex query which addresses each field individually
Build some sort of lookup table which concatenates the fields I want to index and just do a full-text query on that derived table.
(Feel free to edit for clarity; I'm not in it for the rep points.)
If your sql server supports it you can create an indexed view and full text search that; you can use containstable(*,'"chris"') to read all the columns.
If it doesn't support it as the fields are all coming from different tables I think for scalability; if you can easily populate the fields into a single row per record in a separate table I would full text search that rather than the individual records. You will end up with a less complex FTS catalog and your queries will not need to do 4 full text searches at a time. Running lots of separate FTS queries over different tables at the same time is a ticket to query performance issues in my experience. The downside with doing this is you lose the ability to search for Surname on its own; if that is something you need you might need to look at an alternative.
In our app we found that the single table was quicker (we can't rely on customers having enterprise sql at hand); so we populate the data with spaces into an FTS table through an update sp then our main contact lookup runs a search over the list. We have two separate searches to handle finding things with precision (i.e. names or phone numbers) or just for free text. The other nice thing about the table is it is relatively easy and low cost to add further columns to the lookup (we have been asked for social security number for example; to do it we just added the column to the update SP and we were away with little or no impact.
One possibility is to make a view which has these columns: PersonID, ContentType, Content. ContentType would be something like "Email", "PhoneNumber", etc... and Content would hold that. You'd be searching on the Content column, and you'd be able to see what the person's ID is. I'm not 100% sure how full text search works though, so I'm not sure if you could use that on a view.
The FTS can search multiple fields out-of-the-box. The CONTAINS predicate accepts a list of columns to search. Also CONTAINSTABLE.

Possible to search multiple tables with a single query? [MSAccess/SQL Server]

So my goal here is to have a single search field in an application that will be able to search multiple tables and return results.
For example, two of these tables are "performers" and "venues" and there are the following performers: "John Andrews","Andrew Smith","John Doe" and the following venues: "St. Andrew's Church","City Hall". Is there a way to somehow return the first two performers and the first venue for a search of "Andrew"?
My first thought was to somehow get all the tables aggregated into a single table with three columns; "SearchableText","ResultType","ResultID". The first column would contain whatever I want searched (e.g. Performer name), the second would say what is being shown (e.g. Performer) and the third would say the item's ID (note: all my tables have auto-incrementing primary keys for ease). The question for this idea is it possible to somehow do this dynamically or do I have to add code to have a table that automatically fills whenever a new row is updated/added/deleted from the performers and venues table (perhaps via trigger?).
My application is written in MSAccess (I know, I know, but I have no choice) on top of a SQL Server backend. I'd prefer this happen through MSAccess so I don't have to have a "searchme" table sitting on my SQL Server but any good result is acceptable :)
I think you are looking for the "union" sql keyword
I'd use full text indexing in SQL server, have a single table with your searchable text, and forign keys in your main tables that link to the search table. This way you can order your results by relevance.
I think you have a schema problem. Querying a UNION is almost always evidence of that (though not in all cases).
The question to me is:
What are you returning as your result?
If you find a person, are you displaying a list of people?
Or if you find a venue, a list of venues?
Or a mix of both?
I would say that if you want to return a list of both, then you'd want something like this:
SELECT tblPerson.PersonID, tblPerson.LastName & ", " & tblPerson.FirstName, "Person"
FROM tblPerson
WHERE tblPerson.LastName LIKE "Andrew*"
OR tblPerson.FirstName LIKE "Andrew*"
UNION
SELECT tblVenue.Venue, tblVenue.Venue, "Venue"
FROM tblVenue
WHERE tblVenue.Venue LIKE "Andrew*"
ORDER BY Venue
This will give a list of the matches indicating which is a person and which a venue, and allow you to then select one of those and open a detail view (by checking the value in the third field).
What you definitely don't want to do is this:
SELECT tblPerson.PersonID, tblPerson.LastName & ", " & tblPerson.FirstName, "Person"
FROM tblPerson
UNION
SELECT tblVenue.Venue, tblVenue.Venue, "Venue"
FROM tblVenue
then saving that and trying to query it on the 2nd column. That will be extremely inefficient. You want your WHERE clause to be on fields that can be searched via the index, and that means each subquery of your UNION needs to have an appropriate WHERE clause.

How do you manage "pick lists" in a database

I have an application with multiple "pick list" entities, such as used to populate choices of dropdown selection boxes. These entities need to be stored in the database. How do one persist these entities in the database?
Should I create a new table for each pick list? Is there a better solution?
In the past I've created a table that has the Name of the list and the acceptable values, then queried it to display the list. I also include a underlying value, so you can return a display value for the list, and a bound value that may be much uglier (a small int for normalized data, for instance)
CREATE TABLE PickList(
ListName varchar(15),
Value varchar(15),
Display varchar(15),
Primary Key (ListName, Display)
)
You could also add a sortOrder field if you want to manually define the order to display them in.
It depends on various things:
if they are immutable and non relational (think "names of US States") an argument could be made that they should not be in the database at all: after all they are simply formatting of something simpler (like the two character code assigned). This has the added advantage that you don't need a round trip to the db to fetch something that never changes in order to populate the combo box.
You can then use an Enum in code and a constraint in the DB. In case of localized display, so you need a different formatting for each culture, then you can use XML files or other resources to store the literals.
if they are relational (think "states - capitals") I am not very convinced either way... but lately I've been using XML files, database constraints and javascript to populate. It works quite well and it's easy on the DB.
if they are not read-only but rarely change (i.e. typically cannot be changed by the end user but only by some editor or daily batch), then I would still consider the opportunity of not storing them in the DB... it would depend on the particular case.
in other cases, storing in the DB is the way (think of the tags of StackOverflow... they are "lookup" but can also be changed by the end user) -- possibly with some caching if needed. It requires some careful locking, but it would work well enough.
Well, you could do something like this:
PickListContent
IdList IdPick Text
1 1 Apples
1 2 Oranges
1 3 Pears
2 1 Dogs
2 2 Cats
and optionally..
PickList
Id Description
1 Fruit
2 Pets
I've found that creating individual tables is the best idea.
I've been down the road of trying to create one master table of all pick lists and then filtering out based on type. While it works, it has invariably created headaches down the line. For example you may find that something you presumed to be a simple pick list is not so simple and requires an extra field, do you now split this data into an additional table or extend you master list?
From a database perspective, having individual tables makes it much easier to manage your relational integrity and it makes it easier to interpret the data in the database when you're not using the application
We have followed the pattern of a new table for each pick list. For example:
Table FRUIT has columns ID, NAME, and DESCRIPTION.
Values might include:
15000, Apple, Red fruit
15001, Banana, yellow and yummy
...
If you have a need to reference FRUIT in another table, you would call the column FRUIT_ID and reference the ID value of the row in the FRUIT table.
Create one table for lists and one table for list_options.
# Put in the name of the list
insert into lists (id, name) values (1, "Country in North America");
# Put in the values of the list
insert into list_options (id, list_id, value_text) values
(1, 1, "Canada"),
(2, 1, "United States of America"),
(3, 1, "Mexico");
To answer the second question first: yes, I would create a separate table for each pick list in most cases. Especially if they are for completely different types of values (e.g. states and cities). The general table format I use is as follows:
id - identity or UUID field (I actually call the field xxx_id where xxx is the name of the table).
name - display name of the item
display_order - small int of order to display. Default this value to something greater than 1
If you want you could add a separate 'value' field but I just usually use the id field as the select box value.
I generally use a select that orders first by display order, then by name, so you can order something alphabetically while still adding your own exceptions. For example, let's say you have a list of countries that you want in alpha order but have the US first and Canada second you could say "SELECT id, name FROM theTable ORDER BY display_order, name" and set the display_order value for the US as 1, Canada as 2 and all other countries as 9.
You can get fancier, such as having an 'active' flag so you can activate or deactivate options, or setting a 'x_type' field so you can group options, description column for use in tooltips, etc. But the basic table works well for most circumstances.
Two tables. If you try to cram everything into one table then you break normalization (if you care about that). Here are examples:
LIST
---------------
LIST_ID (PK)
NAME
DESCR
LIST_OPTION
----------------------------
LIST_OPTION_ID (PK)
LIST_ID (FK)
OPTION_NAME
OPTION_VALUE
MANUAL_SORT
The list table simply describes a pick list. The list_ option table describes each option in a given list. So your queries will always start with knowing which pick list you'd like to populate (either by name or ID) which you join to the list_ option table to pull all the options. The manual_sort column is there just in case you want to enforce a particular order other than by name or value. (BTW, whenever I try to post the words "list" and "option" connected with an underscore, the preview window goes a little wacky. That's why I put a space there.)
The query would look something like:
select
b.option_name,
b.option_value
from
list a,
list_option b
where
a.name="States"
and
a.list_id = b.list_id
order by
b.manual_sort asc
You'll also want to create an index on list.name if you think you'll ever use it in a where clause. The pk and fk columns will typically automatically be indexed.
And please don't create a new table for each pick list unless you're putting in "relationally relevant" data that will be used elsewhere by the app. You'd be circumventing exactly the relational functionality that a database provides. You'd be better off statically defining pick lists as constants somewhere in a base class or a properties file (your choice on how to model the name-value pair).
Depending on your needs, you can just have an options table that has a list identifier and a list value as the primary key.
select optionDesc from Options where 'MyList' = optionList
You can then extend it with an order column, etc. If you have an ID field, that is how you can reference your answers back... of if it is often changing, you can just copy the answer value to the answer table.
If you don't mind using strings for the actual values, you can simply give each list a different list_id in value and populate a single table with :
item_id: int
list_id: int
text: varchar(50)
Seems easiest unless you need multiple things per list item
We actually created entities to handle simple pick lists. We created a Lookup table, that holds all the available pick lists, and a LookupValue table that contains all the name/value records for the Lookup.
Works great for us when we need it to be simple.
I've done this in two different ways:
1) unique tables per list
2) a master table for the list, with views to give specific ones
I tend to prefer the initial option as it makes updating lists easier (at least in my opinion).
Try turning the question around. Why do you need to pull it from the database? Isn't the data part of your model but you really want to persist it in the database? You could use an OR mapper like linq2sql or nhibernate (assuming you're in the .net world) or depending on the data you could store it manually in a table each - there are situations where it would make good sense to put it all in the same table but do consider this only if you feel it makes really good sense. Normally putting different data in different tables makes it a lot easier to (later) understand what is going on.
There are several approaches here.
1) Create one table per pick list. Each of the tables would have the ID and Name columns; the value that was picked by the user would be stored based on the ID of the item that was selected.
2) Create a single table with all pick lists. Columns: ID; list ID (or list type); Name. When you need to populate a list, do a query "select all items where list ID = ...". Advantage of this approach: really easy to add pick lists; disadvantage: a little more difficult to write group-by style queries (for example, give me the number of records that picked value X".
I personally prefer option 1, it seems "cleaner" to me.
You can use either a separate table for each (my preferred), or a common picklist table that has a type column you can use to filter on from your application. I'm not sure that one has a great benefit over the other generally speaking.
If you have more than 25 or so, organizationally it might be easier to use the single table solution so you don't have several picklist tables cluttering up your database.
Performance might be a hair better using separate tables for each if your lists are very long, but this is probably negligible provided your indexes and such are set up properly.
I like using separate tables so that if something changes in a picklist - it needs and additional attribute for instance - you can change just that picklist table with little effect on the rest of your schema. In the single table solution, you will either have to denormalize your picklist data, pull that picklist out into a separate table, etc. Constraints are also easier to enforce in the separate table solution.
This has served us well:
SQL> desc aux_values;
Name Type
----------------------------------------- ------------
VARIABLE_ID VARCHAR2(20)
VALUE_SEQ NUMBER
DESCRIPTION VARCHAR2(80)
INTEGER_VALUE NUMBER
CHAR_VALUE VARCHAR2(40)
FLOAT_VALUE FLOAT(126)
ACTIVE_FLAG VARCHAR2(1)
The "Variable ID" indicates the kind of data, like "Customer Status" or "Defect Code" or whatever you need. Then you have several entries, each one with the appropriate data type column filled in. So for a status, you'd have several entries with the "CHAR_VALUE" filled in.

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