I have a table PatientChartImages. It has a column ChartImage, which contains the binary of images. Now, we are planning to create a separate table which will contain the Binary of Images and will join both the tables to get requisite data. Now, we do not want to change the front end and I cannot use triggers. So, is there any way by which if a query refers to ChartImage column of PatientChartImages, it picks data from the third table? Please suggest.
I think inner-join does this. I've only overheard it's use - but this might lead you towards your answer.
Related
I am sorry for the lack of notation in my question but I am not too familiar with SQL. Despite searching the internet for a decent amount of hours, I couldn't find that how to do efficiently what I wanted to do, but that is maybe because I am not familiar with the notation. Here comes the question:
I want to create a table, say Forms, in which each Form row has an ID, some metadata and a pointer(?) to the table of that Form row, lets say Form12 table, which directs me to Form12 table. I need it because every Form has different number, name and type of columns depending on users configuration for a particular Form.
So, I thought I can put the Table ID of Form12 as a column to Form table. But is this approach considered OK, or is there a better way to do it?
Thank you for your time.
Storing the names of tables in a column is generally not a good solution in a relational database. In order to use the information, you need to use dynamic SQL.
I would instead ask why you cannot store the information in a single table or well-defined sets of tables. Postgres has lots of options to help with this:
NULL data values, so columns do not need to be filled in.
Table inheritance, so tables can share columns.
JSON columns to support a flexible set of columns.
Entity-attribute-value (EAV) data models, which allow for lots of flexibility.
Our use case for BigQuery is a little unique. I want to start using Date-Partitioned Tables but our data is very much eventual. It doesn't get inserted when it occurs, but eventually when it's provided to the server. At times this can be days or even months before any data is inserted. Thus, the _PARTITION_LOAD_TIME attribute is useless to us.
My question is there a way I can specify the column that would act like the _PARTITION_LOAD_TIME argument and still have the benefits of a Date-Partitioned table? If I could emulate this manually and have BigQuery update accordingly, then I can start using Date-Partitioned tables.
Anyone have a good solution here?
You don't need create your own column.
_PARTITIONTIME pseudo column still will work for you!
The only what you will need to do is insert/load respective data batch into respective partition by referencing not just table name but rather table with partition decorator - like yourtable$20160718
This way you can load data into partition that it belong to
My requirement is simple...
I have a table in SQL with more than 300 columns in it and I need to compare the data present in those columns with the source table.
Now every time I cannot waste my time finding where is the column I want to compare the data by dragging.
So my question is...Is there any short cut or code to go to a specific column when in case of a large table as in my requirement.
Any help is highly appreciated.
There are multiple ways to compare two tables based on the requirement.
If your source can be accessible for you then simple MINUS will do.
In Oracle:
SELECT COL1,COL2,COL3.... FROM SOURCE
MINUS
SELECT COL1,COL2,COL3.... FROM TARGET
In Informatica you can generate MD5 hash for the column you want to compare from both Source and Target and check whether both hashes are matching.
I've got and sql express database I need to extract some data from. I have three fields. ID,NAME,DATE. In the DATA column there is values like "654;654;526". Yes, semicolons includes. Now those number relate to another table(two - field ID and NAME). The numbers in the DATA column relate to the ID field in the 2nd table. How can I via sql do a replace or lookup so instead of getting the number 654;653;526 I get the NAME field instead.....
See the photo. Might explain this better
http://i.stack.imgur.com/g1OCj.jpg
Redesign the database unless this is a third party database you are supporting. This will never be a good design and should never have been built this way. This is one of those times you bite the bullet and fix it before things get worse which they will. Yeu need a related table to store the values in. One of the very first rules of database design is never store more than one piece of information in a field.
And hopefully those aren't your real field names, they are atriocious too. You need more descriptive field names.
Since it a third party database, you need to look up the split function or create your own. You will want to transform the data to a relational form in a temp table or table varaiable to use in the join later.
The following may help: How to use GROUP BY to concatenate strings in SQL Server?
This can be done, but it won't be nice. You should create a scalar valued function, that takes in the string with id's and returns a string with names.
This denormalized structure is similar to the way values were stored in the quasi-object-relational database known as PICK. Cool database, in many respects ahead of its time, though in other respects, a dinosaur.
If you want to return the multiple names as a delimited string, it's easy to do with a scalar function. If you want to return the multiple rows as a table, your engine has to support functions that return a type of TABLE.
I would like to know if there's a way to add a column to an SQL Server table after it's created and in a specific position??
Thanks.
You can do that in Management-Studio. You can examine the way this is accomplished by generating the SQL-script BEFORE saving the change. Basically it's achieved by:
removing all foreign keys
creating a new table with the added column
copying all data from the old into the new table
dropping the old table
renaming the new table to the old name
recreating all the foreign keys
In addition to all the other responses, remember that you can reorder and rename columns in VIEWs. So, if you find it necessary to store the data in one format but present it in another, you can simply add the column on to the end of the table and create a single table view that reorders and renames the columns you want to show. In almost every circumstance, this view will behave exactly like the original table.
The safest way to do this is.
Create your new table with the correct column order
Copy the data from the old table.
Drop the Old Table.
The only safe way of doing that is creating a new table (with the column where you want it), migrating the data, dropping the original table, and renaming the new table to the original name.
This is what Management Studio does for you when you insert columns.
As others have pointed out you can do this by creating a temp table moving the data and droping the orginal table and then renaming the other table. This is stupid thing to do though. If your table is large, it could be very time-consuming to do this and users will be locked out during the process. This issomething you NEVER want to do to any table in production.
There is absolutely no reason to ever care what order the columns are in a table since you should not be relying on column order anyway (what if someone else did this same stupid thing?). No queries should use select * or ordinal positions to get columns. If you are doing this now, this is broken code and needs to be fixed immediately as the results are not always going to be as expected. For instance if you do insert a column where you want it and someone else is using select * for a report, suddenly the partnumber is showing up in the spot that used to hold the Price.
By doing what you want to do, you may break much more than you fix by putting the column where you personally want it. Column order in tables should always be irrelevant. You should not be doing this every time you want columns to appear in a differnt order.
With Sql Server Management Studio you can open the table in design and drag and drop the column wherever you want
As Kane says, it's not possible in a direct way. You can see how Management Studio does it by adding a column in the design mode and checking out the change script.
If the column is not in the last position, the script basically drops the table and recreates it, with the new column in the desired position.
In databases table columns don't have order.
Write proper select statement and create a view
No.
Basically, SSMS behind the scenes will copy the table, constraints, etc, drop the old table and rename the new.
The reason is simple - columns are not meant to be ordered (nor are rows), so you're always meant to list which columns you want in a result set (select * is a bit of a hack)