In Microsoft SQL Server 2008 R2, let's say my database has the following view:
create view [dbo].[MyView]
(
[MyColumnA]
)
AS
(SELECT MyColumnB FROM MyTable)
Now let's suppose I only know that there is a view called MyView that has a column called MyColumnA, but I don't know that it maps to MyTable.ColumnB. What is the easiest/fastest way to determine which table and column MyView.ColumnA maps to? Is there a query that can tell me this? Something like:
SELECT TABLE_NAME, TABLE_COLUMN_NAME
FROM INFORMATION_SCHEMA.VIEW_MAPPINGS
WHERE VIEW_NAME = 'MyView' AND VIEW_COLUMN_NAME = 'MyColumnA'
This query would return [MyTable, MyColumnB].
Currently I have to find the view in SSMS Object Explorer, right click it and generate the create script, then search for the name of the view's column. Then I note which ordinal position it is in the view (let's say 4th column), and have to find the corresponding 4th column in the select statement. The select statement will most likely be using a table alias, so then I have to look through the JOIN statements to find the table name based on the alias.
This is quite time consuming, and I'm hoping to find a faster way, if not by a query then perhaps by some other process that is faster or easier than mine.
SP_DEPENDS should work
SP_DEPENDS 'MyView'
Related
I have the following query:
SELECT * FROM MailingList
There are about 20+ columns in the MailingList table, one which is called Address. This column has some fields which contain commas, which I need to take out. So I updated my query to:
SELECT REPLACE(Address, ',', '') AS Address, * FROM MailingList
But now I have two Address columns. Is there a way to only display one Address column while still using the wildcard (*) for all the other columns?
There is not a way to do this, though listing the columns you want explicitly is a good idea anyway.
You can trick as following query:
Get the data into a temp table
Drop the cloumns that are not needed
Get results and drop temp table
SELECT *, REPLACE(Address, ',', '') AS Address2
INTO #TempTable
FROM MailingList
ALTER TABLE #TempTable
DROP COLUMN [Address]
SELECT * FROM #TempTable
DROP TABLE #TempTable
I agree with Shadow - avoid using the * wild card if you can...
I know listing out ALL of the columns in select statement for big tables is a pain so here is a quick short cut you may not be aware of: In SQL Server Management Studio, browse through the object explorer and find the table you want to select from (MailingList). Right-click it to view the context menu and choose "Script Table as" then "SELECT TO" then "New Query Editor Window". This will create a new select statement with each column spelled out. In the future, use this method to create select statements, queries, procedures, etc. rather then the * wildcard. Performance is better and it just looks nicer :-)
Then you can solve your alias issue with the replace function.
Normally a full table from a view is created by:
SELECT *
INTO dbo.table
FROM view
But I have a very complex view (which worked in SQL Server 2005), but in SQL Server 2008 Express, I get the error message:
Internal error: An expression services limit has been reached. Please
look for potentially complex expressions in your query, and try to
simplify them.
By eliminating the header <CREATE VIEW viewname AS> I managed to do a normal query.
So I want to copy this query into a new table with all columns of the query.
The query (or the view) consists of 3 tables with a lot of joins and so on.
My question is, how is it possible to get my problem solved?
SELECT *
INTO dbo.table
FROM <here is my complex query, beginning with select>
does not work.
Do it in two steps :
First create your table with the appropriate column names and type.
Use then an INSERT INTO .... SELECT statement like this :
INSERT INTO yourNewTable
(column1,
column2,
...
)
SELECT (your complex query)
Explicitely listing the columns is not mandatory if the result of your query directly match the structure of your target table. Nonetheless it is still advised for maintenability reasons.
I'm new to SQL Server programming, so this may or may not be a stupid question.
So, first I do not know what my input table is (my task is supposed to work with ANY table).
Second, I get the column names using sp_help and then I select only that column into another table. Now I need the rows from COLUMN_NAME to be the names of god knows how many columns into some new table.
I tried something using PIVOT, but I can't seem to make it work.
It sounds like you want to access the metadata tables. Something like this may put you in the right direction:
insert into column_name(name)
select column_name
from information_schema.columns
where table_name = XXX <----- YOUR TABLE GOES HERE
I'm using Oracle DB and I would like to write a SQL query that I could then call with JDBC. I'm not very familiar with SQL so if someone can help me, that could be great ! Here is the problem. I have a table MY_TABLE wich contains a list of another tables, and I would like to keep only the nonempty tables and those that their names start by a particular string.
The query I wrote is the following :
select TABLE_NAME
from MY_TABLE
where TABLE_NAME like '%myString%'
and (select count(*) from TABLE_NAME where rownum=1)<>0
order by TABLE_NAME;`
The problem comes from the second SELECT, but I don't know how can I do to use the TABLE_NAME value.
Does someone have an idea ?
Thanks.
[Added from comments]
Actually, I need to test the V$ views contained in the ALL_CATALOG table. But if I can find another table where all these views are contained too and with a NUM_ROWS column too, it would be perfect !
Standard versions of SQL do not allow you to replace 'structural elements' of the query, such as table name or column name, with variable values or place-holders.
There are a few ways to approach this.
Generate a separate SQL statement for each table name listed in MY_TABLE, and execute each in turn. Brute force, but effective.
Interrogate the system catalog directly.
Investigate whether there are JDBC metadata operations that allow you to find out about the number of rows in a table without being tied to the system catalog of the specific DBMS you are using.
Can you use oracle view USER_TABLES? then query will be much easier
select TABLE_NAME
from USER_TABLES
where TABLE_NAME like '%myString%'
and Num_ROWS > 0
order by TABLE_NAME;`
how to convert result of an select sql query into a new table in msaccess ?
You can use sub queries
SELECT a,b,c INTO NewTable
FROM (SELECT a,b,c
FROM TheTable
WHERE a Is Null)
Like so:
SELECT *
INTO NewTable
FROM OldTable
First, create a table with the required keys, constraints, domain checking, references, etc. Then use an INSERT INTO..SELECT construct to populate it.
Do not be tempted by SELECT..INTO..FROM constructs. The resulting table will have no keys, therefore will not actually be a table at all. Better to start with a proper table then add the data e.g. it will be easier to trap bad data.
For an example of how things can go wrong with an SELECT..INTO clause: it can result in a column that includes the NULL value and while after the event you can change the column to NOT NULL the engine will not replace the NULLs, therefore you will end up with a NOT NULL column containing NULLs!
Also consider creating a 'viewed' table e.g. using CREATE VIEW SQL DDL rather than a base table.
If you want to do it through the user interface, you can also:
A) Create and test the select query. Save it.
B) Create a make table query. When asked what tables to show, select the query tab and your saved query.
C) Tell it the name of the table you want to create.
D) Go make coffee (depending on taste and size of table)
Select *
Into newtable
From somequery