This is the problem:
I have a table with unknown number of columns. all the columns are real.
Assuming there is only one row in that table, I need a method to determine if there is a value other than NULL in that table/row.
I don't know the number of columns nor their name at run-time (and don't want to use c cursor)
SQL Server 2005
I appreciate your help.
Here's one way - CHECKSUM() returns no value if all values in the row are NULL:
create table #t (col1 real, col2 real, col3 real)
select checksum(*) from #t
if ##rowcount = 0
print 'All values are NULL'
else
print 'Non-NULL value(s) found'
drop table #t
On the other hand, I don't really know if this is what you're doing: a "temporary table built in memory" sounds like something you're managing yourself. With more information about what you're trying to achieve, we might be able to suggest a better solution.
And by the way, there is nothing wrong with a single-row table for storing settings. It has the big advantage that each setting has a separate data type, can have CHECK constraints etc.
Sounds like you're doing some kind of a settings/properties table, based on the fact that you know you only have 1 row in it. This is the wrong way to do it, if you need to have dynamic properties; instead have a table with 2 columns: option and value. Then for each dynamic property, you'll store one row.
Related
I am having an issue with an sql query used in job automation
The procedure inserts data from a source table(48 columns) to destination table(49 columns where the 49th/last column is NOT in the source table). But all columns in the destination and source table accept null, so that shouldn't be an issue copying from 48 columns to 49 columns.
It throws this error :
Column name or number of supplied values does not match table definition. [SQLSTATE 21S01] (Error 213). The step failed.
It should just insert null into the 49th column and I have checked the column names and they correspond.
Let's treat this like I can't delete the 49th column.
Please what can I do here?
Accepting NULL doesn't mean you can specify 49 cols and 48 values in the sql INSERT statement. The number of columns and number of values must match exactly. Either drop extra column from INSERT list or add 49th value (NULL I guess) to the values list. In both cases if column is NULLable, it will be set to NULL.
First, if you have code that's not working, you should post it so we can tell for sure what's happening. But I'd be pretty willing to bet you're trying to short cut the process and use something like this:
INSERT tableB
SELECT *
FROM tableA
But the tables don't have the same number of columns, so the SQL Engine doesn't know which source column goes into which destination column. You need to provide an explicit list so it knows which one you intend to ignore:
INSERT tableB
(
col1,
col2,
...
col48
)
SELECT
col1,
col2,
...
col48
FROM tableA;
I have a table with two columns built from another table of names, one identity and one a name like this:
ID---Name
1----Mike
2----Jeff
3----Robert
...down to however many
Could be 10 rows, could be 100. This will vary depending on input from other tables that are always changing but never be over 160 or so.
Now, pairings of names will have some meaning and thus a decimal data type score will be associated with said pairing (how at this point doesn’t matter, just need to build it for now...numbers just illustrative). I envision a matrix kind of like this:
ID------Name------Mike-------Jeff--------Robert-------- ...out to however many
1 -------Mike-------NULL------100.1------5.4-------- ...out to however many
2 -------Jeff---------100.1------NULL-----21.23--------- ...out to however many
3 ------Robert-------5.4--------21.23-----NULL---------...out to however many
…down to however many happen to be in the first table…
Maybe this isn’t quite the most optimal way to go (Yes, I know there are duplicates in the table but I plan to structure the queries such that the duplicates are ignored) but at this point am not aware of many viable options. After searching around, I thought maybe I wanted a pivot but that doesn’t seem to fit what I have here because I’m leaving the names in the column and associating them as column heads for a paired score. Then I thought maybe I wanted to store a variable as the value of each row and then add them as the columns. That was no help. My latest iteration was maybe creating a temp table as an exact copy with and identity column, then trying to select the specific name by the identity and looping through them but I can’t even seem to grab the first name and make it a column name in addition to a row value under the name column...see below
--create a table of names with an identity column
CREATE TABLE myTable2
(
ID INT IDENTITY(1,1),
Name VARCHAR(5),
);
--add names to the table from a different table
INSERT INTO myTable1 (Name)
SELECT Name
FROM myTable1
--create a temp table with the same values
SELECT ID, Name
INTO #new
FROM myTable2
GROUP BY ID, Name
--insert name from first row as a column head
INSERT INTO myTable2 (SELECT Number FROM #new WHERE ID =1)
So, in the last bit there, INSERT INTO”, I want to copy the names, in this instance “Mike” and make it ALSO a column head in the same table where it is a row (like in my second table). I get an error message that the syntax is not correct for the statement. Why isn’t this allowed? How can I get it to do what I want? It also has been suggested by someone that knows way more about this stuff than me, that maybe instead of building the table as a matrix, build it as below. It is possible here to get rid of the duplicates this way and I would except I have no idea where to even begin doing this…
Name1-----------Name2-----------Calculated Value
Mike--------------Mike-------------NULL
Jeff---------------Mike-------------100.1
Robert-------------Mike-------------5.4
Mike--------------Jeff-------------100.1
Jeff----------------Jeff-------------NULL
Robert------------Jeff-------------21.23
Mike--------------Robert-----------5.4
Jeff---------------Robert-----------21.23
Robert------------Robert-----------NULL
...etc
Any help suggestions or pointing of me in the right and most appropriate direction would be greatly appreciated!
EDIT: Here's how I solved my problem. Looks like the Cartesian product was the way to go. Thanks #Alex Kudryashev
--create a table of cross joined names
CREATE TABLE cartNames
(
Name1 VARCHAR(5),
Name2 VARCHAR(5),
);
--create two temporary tables from a source table of names
SELECT Name AS Name1
INTO #name1
FROM names
GROUP BY Name
SELECT Name AS Name2
INTO #Name2
FROM names
GROUP BY Name
--populate the Cartesian table
INSERT INTO cartNames
SELECT * FROM #name1 CROSS JOIN #name2
--get rid of the temp tables
DROP TABLE #Name1
DROP TABLE #Name2
--add columns and populate calculated scores
---
It looks like you want to create a Cartesian Product. There is very easy way to do so.
declare #tbl table(name varchar(10))
insert #tbl(name) values('MIke'),('Jeff'),('Robert')
select t1.name name1,t2.name name2, some_udf(t1.name,t2.name) calc_value
from #tbl t1 cross join #tbl t2
I would like to be able to add columns to a table with cells who's values are computed by need at 'querytime' when (possibly) selecting over them.
Are there some established ways of doing this?
EDIT: Okay I can do without the 'add columns'. What I want is to make a select query which searches some (if they exist) rows with all needed values computed (some function) and also fills in some of the rows which does not have all needed values computed. So each query would do it's part in extending the data a bit.
(Some columns would start out as null values or similar)
I guess I'll do the extending part first and the query after
You use select expression, especially if you don't plan to store the calculation results, or they are dependant on more than one table. An example, as simple as it could be:
SELECT id, (id+1) as next_id FROM table;
What type of database are you asking for? If it is SQL Server then you can use the computed columns by using the AS syntax.
Eg:
create table Test
(
Id int identity(1,1),
col1 varchar(2) default 'NO',
col2 as col1 + ' - Why?'
)
go
insert into Test
default values
go
select * from Test
drop table Test
In the SQL world it's usually expensive to add a column to an existing table so I'd advise against it. Maybe you can manage with something like this:
SELECT OrderID,
ProductID,
UnitPrice*Quantity AS "Regular Price",
UnitPrice*Quantity-UnitPrice*Quantity*Discount AS "Price After Discount"
FROM order_details;
If you really insist on adding a new column, you could go for something like (not tested):
ALTER TABLE order_details ADD column_name datatype
UPDATE order_details SET column_name = UnitPrice+1
You basically ALTER TABLE to add the new column, then perform an UPDATE operation on all the table to set the value of the newly added column.
First off, i should say up front that i am not a very strong SQL person, so please be gentle :)
I need to perform about 400 inserts into a particular table. The data that i will be using for these inserts, i can collect from a SELECT statement that runs off a different table. I only need the data from 1 column from this table.
So, im hoping someone can help me write the SQL that will basically take the list of id's that are returned from my select, and use that list to do a mass insert into another table.
In psuedocode, something like this:
Select BankID from BankTable; - this returns 300 rows
Insert Into AccountTable -- this will add all 300 rows into the 2nd table
Values
(BankID)
thanks in advance guys...
Very simple, you basically said it. :-)
INSERT Into AccountTable (BankId, SecondColumn) SELECT BankId,'XXX' as staticText FROM BankTable;
It can be done in one statement:
Insert Into AccountTable (bankid)
Select BankID from BankTable
This assumes that the column in AccountTable is also named bankid; if not, just set the name appropriately in the parenthesis.
Keep in mind your INSERT statement must include the columns if the select statement does not match your table definition precisely.
INSERT AccountTable (BankID)
SELECT BankID
FROM BankTable
For multiple columns simply include the column list:
INSERT AccountTable (BankID, BankName)
SELECT BankID, BankName
FROM BankTable
You can also run into type conversion issues if the data types of the columns don't match (i.e. integer fields won't take alpha characters, etc.), but it is not a necessity that the column names match. Just get the order of columns and types right and you should be good.
certain fields in our database contain calculated functions e.g.
select lastname + ', ' + firstname as fullname from contact where contact.id =$contact$
when viewing the field the correct data is shown (i assume this is because when you open the record, the calculation is executed). however, the data is not 'stored' to the field, and therefore is null until the record is opened. is it possible to 'store' the result to the field, making it possible to search the data?
many thanks
james
EDIT
it is not possible for me to create computed_columns using our software.
the above field is a text feild where either 1) a user can manual type in the required data or 2) the database can generate the answer for you (but only whilst you are looking at the record). i know that if I run the following:
Select * from contact where contact.id =$contact$ for xml auto
i only get lastname, firstname - so i know that the fullname field does not retain its information.
If you are using computed columns in sql server, the column is already searchable regardless of whether the calculation result is stored or not. However, if you would like to make it so that the calculation is not run each time you read the row, you can change that under row properties in your Modify Table GUI.
Use the PERSISTED key word when you create the column
From BOL:
PERSISTED
Specifies that the SQL Server Database Engine will physically store the computed values in the table, and update the values when any other columns on which the computed column depends are updated. Marking a computed column as PERSISTED lets you create an index on a computed column that is deterministic, but not precise. For more information, see Creating Indexes on Computed Columns. Any computed columns that are used as partitioning columns of a partitioned table must be explicitly marked PERSISTED. computed_column_expression must be deterministic when PERSISTED is specified.
This isn't the way computed columns work in SQL Server, so I suspect this is something your client application is doing. How are you looking at the data when the value is computed correctly? Does it work when you view the data in SSMS?
Take a look at http://msdn.microsoft.com/en-us/library/ms191250(v=SQL.90).aspx to see how to create computed columns properly.
eg.
create table TestTable
(a int,
b int,
c as a + b)
insert into TestTable (a,b)
values (1,2)
select * from TestTable
where c = 3
This query is based on the computed column and it returns the row that's been inserted.
You need to use the PERSISTED option on a column when you use CREATE TABLE e.g.
CREATE TABLE test (col_a INT, col_b INT, col_c AS col_A * col_B PERSISTED)