What is the best tool or method to map a SQL Server query to a SQL Server table with different column names?
Secondly and separately, is there a tool that considers objects and values in a different language. I attempted to use Redgate; however, the SQL Compare function does not allow for mapping with different column names.
Mapping is needed for different queries from different agencies who each use different table/column names. In some cases, the language for the columns and values are different (i.e., Italian, Spanish).
SQL Data Compare (not SQL Compare) lets you compare a table against a view. So If you create a view on the second table, giving it the column names used in the first table, then you can use the Tables and Views tab to map the table with the view.
Make sure you "include views" in the Options tab to see the views listed in the tables and views tab.
Related
I want to create new table with empty columns and specify the datatype later. Is it possible? I try to do so on myscompiler.io and it works. I don't know if it's just possible in such site or is it actually possible to create that once I use other tools to write my SQL.
No. The SQL syntax requires that a table be well-defined, with column names and data types. This is true in every database that I can think of.
You could possibly do what you want in one of three ways:
Your database might support some sort of generic type which you could use to define the column. For instance, SQL Server has a sql_variant type.
You could define the table with a specific type such as a string and change the type later using alter table.
You could define the table with a single primary key column and add columns as you decide what they are.
I don't recommend any of these approaches. Instead, I would suggest that you need to re-think how your application is structured. Tables represent entities and entities have properties. Generally when using databases, these things are known before you start doing any work. There may be some cases where dynamic table creation is useful, but that is definitely not the common approach when using databases.
Context
I have three tables in my SQL Server database: 1) School, 2) College, 3) University.
Then I have another table: Tags.
Each of the three tables (School, College, University) can have Tags associated with them. For which purpose I have three association tables: SchoolTags, CollegeTags, UniversityTags.
Problem
I am trying to create a user-defined function that will take the name of association table as parameter (i.e. 'SchoolTags') and the Id of the entity (school/college/university) and will return a list of tags associated with that entityId.
The issue I am having is I have got to join Tags with a table whose name will come in as parameter. For that I am creating a dynamic query. And we can not run dynamic queries in SQL Server user-defined functions.
Question
Any idea how can that be acheived?
Note: I want separate association tables as I have created and do not want to convert them into a generic association table and I do not want to add If-Else based on table names in my function so that if a new association table is created, I do not need to update my function.
I am using Microsoft SQL Server.
Whatever language you are using, you would probably use if:
begin
if table = 'school' then
begin
. . .
end;
else if table = 'college' then
. . .
end;
The exact syntax depends on the scripting language for the database you are using.
What you desire is impossible. You cannot pass a table name as a parameter to a UDF and use dynamic sql in the UDF to then create and execute a statement that is specific to the table passed as the argument. You already know that you have no choice but to use if-else statements in your UDF to achieve your goal - it is your pipe-dream of "never having to update (or verify) your code when the schema changes" (yes - I rephrased it to make your issue more obvious) that is a problem.
There are likely to be other ways of implementing some useful functionality - but I suggest that you are thinking too far ahead and trying to implement generic functions without a clear purpose. And that is a very difficult and trouble-prone path that requires sophisticated tsql skills.
And to re-iterate the prior responses, you have a schema problem. You purposely created three different entities - and now you want a common function to use with any of them. So before you spend much time on this particular aspect, you should take some time to think carefully about how you intend to use (i.e., write queries against) these tables. If you find yourself using unions frequently to combine these entities into a common resultset, then you have might have a mismatch between your actual business and your model (schema) of it.
Consider normalizing your database in related, logical groupings for one EducationInstitution table and one JoinEducTags table. Those tables sound like they maintain the same structure but of different typology and hence should be saved in one table with different Type field for School, College, University, etc.
Then, add necessary constraints, primary/foreign keys for the one-to-many relationship between all three sets:
You never want to keep restructuring your schema (i.e., add tables) for each new type. With this approach, your user-defined function would just need to receive value parameters not identifiers like tables to be run in dynamic querying. Finally, this approach scales better with efficient storage. And as you will see normalization saves on complex querying.
I had a look in the tables I am using in my database based on Rapid SQL. In one of the table i was just checking columns used in that table. I used sp_help table_name to find out the details of columns, datatypes and other things. I found some data types as T_gender_domain, T_name_domain, T_phone_domain. Are they used as a user defined data types???
The scenario is that, I have 2 database tables A and B. The table B is an upgraded version of the table A. (ie It might possibly have different field names and some extra fields). I need to compare these 2 tables to inform the user about these extra fields and propose to him a mapping of the fields between the tables.
Currently I am thinking of comparing them using info like field name, data element and domain in that order.
Is there a standard way to do this? Thanks in advance.
There is no standard tool to do this - why would you want to do it this way anyway? The canonical way is to extend the original table and fill the new fields in place.
I have multiple database files which exist in multiple locations with exactly similar structure. I understand the attach function can be used to connect multiple files to one database connection, however, this treats them as seperate databases. I want to do something like:
SELECT uid, name FROM ALL_DATABASES.Users;
Also,
SELECT uid, name FROM DB1.Users UNION SELECT uid, name FROM DB2.Users ;
is NOT a valid answer because I have an arbitrary number of database files that I need to merge. Lastly, the database files, must stay seperate. anyone know how to accomplish this?
EDIT: an answer gave me the idea: would it be possible to create a view which is a combination of all the different tables? Is it possible to query for all database files and which databases they 'mount' and then use that inside the view query to create the 'master table'?
Because SQLite imposes a limit on the number of databases that can be attached at one time, there is no way to do what you want in a single query.
If the number can be guaranteed to be within SQLite's limit (which violates the definition of "arbitrary"), there's nothing that prevents you from generating a query with the right set of UNIONs at the time you need to execute it.
To support truly arbitrary numbers of tables, your only real option is to create a table in an unrelated database and repeatedly INSERT rows from each candidate:
ATTACH DATABASE '/path/to/candidate/database' AS candidate;
INSERT INTO some_table (uid, name) SELECT uid, name FROM candidate.User;
DETACH DATABASE candidate;
Some cleverness in the schema would take care of this.
You will generally have 2 types of tables: reference tables, and dynamic tables.
Reference tables have the same content across all databases, for example country codes, department codes, etc.
Dynamic data is data that will be unique to each DB, for example time series, sales statistics,etc.
The reference data should be maintained in a master DB, and replicated to the dynamic databases after changes.
The dynamic tables should all have a column for DB_ID, which would be part of a compound primary key, for example your time series might use db_id,measurement_id,time_stamp. You could also use a hash on DB_ID to generate primary keys, use same pk generator for all tables in DB. When merging these from different DBS , the data will be unique.
So you will have 3 types of databases:
Reference master -> replicated to all others
individual dynamic -> replicated to full dynamic
full dynamic -> replicated from reference master and all individual dynamic.
Then, it is up to you how you will do this replication, pseudo-realtime or brute force, truncate and rebuild the full dynamic every day or as needed.