I am have two fields in my table:
One is Primary key auto increment value and second is text value.
lets say: xyzId & xyz
So I can easily insert like this
insert into abcTable(xyz) Values('34')
After performing above query it must insert these information
xyzId=1 & xyz=34
and for retrieving I can retrieve like this
select xyzId from abcTable
But for this I have to write down two operation. Cant I retrieve in single/sub query ?
Thanks
If you are on SQL Server 2005 or later you can use the output clause to return the auto created id.
Try this:
insert into abcTable(xyz)
output inserted.xyzId
values('34')
I think you can't do an insert and a select in a single query.
You can use a Store Procedures to execute the two instructions as an atomic operation or you can build a query in code with the 2 instructions using ';' (semicolon) as a separator betwen instructions.
Anyway, for select identity values in SQL Server you must check ##IDENTITY, SCOPE_IDENTITY and IDENT_CURRENT. It's faster and cleaner than a select in the table.
Related
I'm using a PostgreSQL with a Go driver. Sometimes I need to query not existing fields, just to check - maybe something exists in a DB. Before querying I can't tell whether that field exists. Example:
where size=10 or length=10
By default I get an error column "length" does not exist, however, the size column could exist and I could get some results.
Is it possible to handle such cases to return what is possible?
EDIT:
Yes, I could get all the existing columns first. But the initial queries can be rather complex and not created by me directly, I can only modify them.
That means the query can be simple like the previous example and can be much more complex like this:
WHERE size=10 OR (length=10 AND n='example') OR (c BETWEEN 1 and 5 AND p='Mars')
If missing columns are length and c - does that mean I have to parse the SQL, split it by OR (or other operators), check every part of the query, then remove any part with missing columns - and in the end to generate a new SQL query?
Any easier way?
I would try to check within information schema first
"select column_name from INFORMATION_SCHEMA.COLUMNS where table_name ='table_name';"
And then based on result do query
Why don't you get a list of columns that are in the table first? Like this
select column_name
from information_schema.columns
where table_name = 'table_name' and (column_name = 'size' or column_name = 'length');
The result will be the columns that exist.
There is no way to do what you want, except for constructing an SQL string from the list of available columns, which can be got by querying information_schema.columns.
SQL statements are parsed before they are executed, and there is no conditional compilation or no short-circuiting, so you get an error if a non-existing column is referenced.
I have a table. I wrote a function in plpgsql that inserts a row into this table:
INSERT INTO simpleTalbe (name,money) values('momo',1000) ;
This table has serial field called id. I want in the function after I insert the row to know the id that the new row received.
I thought to use:
select nextval('serial');
before the insert, is there a better solution?
Use the RETURNING clause. You need to save the result somewhere inside PL/pgSQL - with an appended INTO ..
INSERT INTO simpleTalbe (name,money) values('momo',1000)
RETURNING id
INTO _my_id_variable;
_my_id_variable must have been declared with a matching data type.
Related:
PostgreSQL next value of the sequences?
Depending on what you plan to do with it, there is often a better solution with pure SQL. Examples:
Combining INSERT statements in a data-modifying CTE with a CASE expression
PostgreSQL multi INSERT...RETURNING with multiple columns
select nextval('serial'); would not do what you want; nextval() actually increments the sequence, and then the INSERT would increment it again. (Also, 'serial' is not the name of the sequence your serial column uses.)
#Erwin's answer (INSERT ... RETURNING) is the best answer, as the syntax was introduced specifically for this situation, but you could also do a
SELECT currval('simpletalbe_id_seq') INTO ...
any time after your INSERT to retrieve the current value of the sequence. (Note the sequence name format tablename_columnname_seq for the automatically-defined sequence backing the serial column.)
I have a table BigTable and a table LittleTable. I want to move a copy of some records from BigTable into LittleTable and then (for these records) set BigTable.ExportedFlag to T (indicating that a copy of the record has been moved to little table).
Is there any way to do this in one statement?
I know I can do a transaction to:
moves the records from big table based on a where clause
updates big table setting exported to T based on this same where clause.
I've also looked into a MERGE statement, which does not seem quite right, because I don't want to change values in little table, just move records to little table.
I've looked into an OUTPUT clause after the update statement but can't find a useful example. I don't understand why Pinal Dave is using Inserted.ID, Inserted.TEXTVal, Deleted.ID, Deleted.TEXTVal instead of Updated.TextVal. Is the update considered an insertion or deletion?
I found this post TSQL: UPDATE with INSERT INTO SELECT FROM saying "AFAIK, you cannot update two different tables with a single sql statement."
Is there a clean single statement to do this? I am looking for a correct, maintainable SQL statement. Do I have to wrap two statements in a single transaction?
You can use the OUTPUT clause as long as LittleTable meets the requirements to be the target of an OUTPUT ... INTO
UPDATE BigTable
SET ExportedFlag = 'T'
OUTPUT inserted.Col1, inserted.Col2 INTO LittleTable(Col1,Col2)
WHERE <some_criteria>
It makes no difference if you use INSERTED or DELETED. The only column it will be different for is the one you are updating (deleted.ExportedFlag has the before value and inserted.ExportedFlag will be T)
Wondering if there is a way to query a SQL Server database and somehow format columns to omit commas in the data if there is any.
Reason for asking is I have 10000+ records and through out the data the varchar have data like 3,25% and other 1%.
I'd prefer not to alter the data in the original table thus asking if a select with other functions would do the trick.
I have thought about selecting all the data into a temp table and stripping the commas but that is a lot of work for every time I do the query.
Any info or if its is possible please reply.
Take a look at the REPLACE function:
SELECT REPLACE(YourColumn, ',', '')
FROM YourTable
Use SQL REPLACE :
REPLACE(YourField,',','')
I have a stored procedure which creates and works with a temporary #table
Some of the queries would be tremendously optimized if that temporary #table would have an index created on it.
However, creating an index within the stored procedure fails:
create procedure test1 as
SELECT f1, f2, f3
INTO #table1
FROM main_table
WHERE 1 = 2
-- insert rows into #table1
create index my_idx on #table1 (f1)
SELECT f1, f2, f3 FROM #table1 (index my_idx) WHERE f1 = 11 -- "QUERY X"
When I call the above, the query plan for "QUERY X" shows a table scan.
If I simply run the code above outside the stored procedure, the messages show the following warning:
Index 'my_idx' specified as optimizer hint in the FROM clause of table '#table1' does not exist. Optimizer will choose another index instead.
This can be resolved when running ad-hoc (outside the stored procedure) by splitting the code above in two batches by addding "go" after index creation:
create index my_idx on #table1 (f1)
go
Now, "QUERY X" query plan shows the use of index "my_idx".
QUESTION: How do I mimique running the "create index" in a separate batch when it's inside the stored procedure? I can't insert a "go" there like I do with the ad-hoc copy above. Please note that I'm aware of the solution of "split up the 'QUERY X' into a separate stored procedure" and am looking for a solution that will avoid that.
P.S. If it matters, this is on Sybase 12 (ASE 12.5.4)
UPDATE:
I have been seeing several references to "schema bumping" during my Googling before posing the question. But that doesn't seem to happen in my case.
You can create a table, populate it, create an index on it and select values
from it in the same porc and have the optimizer fully cost it based on
accurate information. This is called 'schema bumping' and has been in place
since 11.5.1.
The Sybase documentation says that you create and use a temporary index in the same stored procedure:
http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.dc20023_1251/html/optimizer/X26029.htm
I think to get around this you will need to split your stored procedure into at least two parts, one to create and populate the table then build the index, and then a second one to run the select query.
I am not sure how you are getting this problem, might be in older version of Sybase, however with version 12.5.4 I tried executing the same thing as suggested by you but in my case the optimizer correctly suggested the use of index created in the stored procedure. Usually in a stored procedure we do not need to break sql into batches because else we would have been required to have a seperate batch for create table command as well.
In case we try to create index within a same batch (not in a stored procedure) we will do get the same error as specified by you above because we are trying to create an index on a table and then trying to use it within the same batch. Usually the Sybase server will compile the whole batch in one go and hence the problem. But as far as stored procedure is concerned in Sybase 12.5.4 there will be no problem.