I've been banging my head against a brick wall for this for ages.
I am trying to query a table in SQL Express 2010. There are about ten fields in the table. One of the fields is a text field. Some of these have text in them, some have none (I am presuming that they are empty rather than null because querying with Is Null returns an empty set). I want to return the records which have text in this field and not those which are empty. I am guessing that they are empty rather than a blank space.
I have tried the NullIf and IsNull combinations I have seen posted in a few forums but the syntax in these are causing errors. When I put in ' ' as the empty string it is highlighted in red as an error and executing the query just returns an error about can not find such and such with this column name. Sorry I don't have the exact phrase, I'm also having problems with a monitor, etc, etc...
Hope you can help, let me know if you need any more info.
Thanks!
This bit of code shows how to handle NULL and/or "emptry string" text fields:
CREATE TABLE #TextTest (
ID INT IDENTITY,
TextCol TEXT
)
--Add 2 rows with data, 1 with NULL, 1 with "empty string".
INSERT INTO #TextTest (TextCol)
VALUES ('123'),('456'), (NULL), ('')
--This should succeed, but returns the one row with the "empty string".
SELECT *
FROM #TextTest
WHERE TextCol IS NOT NULL
--This should fail
SELECT *
FROM #TextTest
WHERE TextCol <> ''
--This should succeed.
SELECT *
FROM #TextTest
WHERE CAST(TextCol AS VARCHAR(MAX)) <> ''
--Clean up temp table when finished.
--DROP TABLE #TextTest
NOTE: ntext, text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.
Related
I have created a linked server to query some CSV files. The query below works with no errors:
SELECT * FROM OPENQUERY(LINKEDSERVER, 'Select * FROM [import.csv]')
There is a field that could contain either an number or text and the query seems to want to treat it strictly as an integer and returns NULL as the values for any records that have text in that field. All of the records that contain numeric data in that field are displaying properly.
My first thought was maybe that I needed to cast or convert that field to a string to make sure that the query returned data regardless of whether it was numeric or text, but I haven't been able to get that to work. Something like:
SELECT * FROM OPENQUERY(LINKEDSERVER, 'Select cast(field1, varchar(50)) as newfield, field2 FROM [import.csv]')
Does anyone have any ideas?
I have looked and looked and can not find an answer anywhere so I am hoping you guys can help me. I am pulling data from multiple tables using a left join. Some info is not in the right table so it pulls across as NULL. The end user is requesting that all NULL values show as blank. I can easily do this for columns with string datatypes but I have not been able to figure out a way to do this for columns with numeric, int, money, or float datatypes.
See screenshot for simplistic example:
Using SQL Sever 2012
Probably not the answer you want to hear but you might need to convert the numeric columns in your result set to a string type (nvarchar, varchar...etc) and then put a CASE WHEN structure in your SELECT around each one of those columns and check if the value of the field is NULL then print '' the blank string.
Try this;
select
NumberNull=case when ISNUMERIC(YourField)=1 then cast(YourField AS varchar(100)) else '' end
I know strings need to be prefixed with N' in SQL Server (2012) INSERT statements to store them as UNICODE but do they have to be retrieved (SELECT statement) in a certain way as well so they are in UNICODE?
I am able to store international strings correctly with N notation but when I run SELECT query to fetch the records back, it comes as question marks. My query is very simple.
SELECT COLUMN1, COLUMN2 FROM TABLE1
I am looking at other possible reasons that may have caused this issue but at least I want to eliminate the SQL statement above. Should it read COLUMN1 and COLUMN2 columns correctly when they both store UNICODE strings using N notation? Do I have to do anything to the statement to tell it they are UNICODE?
Within management studio you should not need to do anything special to display the correct values. Make sure that the columns in your table is defined as Unicode strings NVARCHAR instead of ANSI strings VARCHAR.
The following example demonstrates the concept:
CREATE TABLE UnicodeExample
(
MyUnicodeColumn NVARCHAR(100)
,MYANSIColumn VARCHAR(100)
)
INSERT INTO UnicodeExample
(
MyUnicodeColumn
,MYANSIColumn
)
VALUES
(
N'איש'
,N'איש'
)
SELECT *
FROM UnicodeExample
DROP TABLE UnicodeExample
In the above example the column MyUnicodeColumn is defined as an NVARCHAR(100) and MYANSIColumn is defined as a VARCHAR(100). The query will correctly return the result for MyUnicodeColumn but will return ??? for MYANSIColum.
How do I alter a sql varchar column to a decimal column when there are nulls in the data?
I thought:
ALTER TABLE table1
ALTER COLUMN data decimal(19,6)
But I just get an error, I assume because of the nulls:
Error converting data type varchar to numeric. The statement has been terminated.
So I thought to remove the nulls I could just set them to zero:
ALTER TABLE table1
ALTER COLUMN data decimal(19,6) NOT NULL DEFAULT 0
but I dont seem to have the correct syntax.
Whats the best way to convert this column?
edit
People have suggested it's not the nulls that are causing me the problem, but non-numeric data. Is there an easy way to find the non-numeric data and either disregard it, or highlight it so I can correct it.
If it were just the presence of NULLs, I would just opt for doing this before the alter column:
update table1 set data = '0' where data is null
That would ensure all nulls are gone and you could successfully convert.
However, I wouldn't be too certain of your assumption. It seems to me that your new column is perfectly capable of handling NULL values since you haven't specified not null for it.
What I'd be looking for is values that aren't NULL but also aren't something you could turn in to a real numeric value, such as what you get if you do:
insert into table1 (data) values ('paxdiablo is good-looking')
though some may argue that should be treated a 0, a false-y value :-)
The presence of non-NULL, non-numeric data seems far more likely to be causing your specific issue here.
As to how to solve that, you're going to need a where clause that can recognise whether a varchar column is a valid numeric value and, if not, change it to '0' or NULL, depending on your needs.
I'm not sure if SQL Server has regex support but, if so, that'd be the first avenue I'd investigate.
Alternatively, provided you understand the limitations (a), you could use isnumeric() with something like:
update table1 set data = NULL where isnumeric(data) = 0
This will force all non-numeric values to NULL before you try to convert the column type.
And, please, for the love of whatever deities you believe in, back up your data before attempting any of these operations.
If none of those above solutions work, it may be worth adding a brand new column and populating bit by bit. In other words set it to NULL to start with, and then find a series of updates that will copy data to this new column.
Once you're happy that all data has been copied, you should then have a series of updates you can run in a single transaction if you want to do the conversion in one fell swoop. Drop the new column and then do the whole lot in a single operation:
create new column;
perform all updates to copy data;
drop old column;
rename new column to old name.
(a) From the linked page:
ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($).
Possible solution:
CREATE TABLE test
(
data VARCHAR(100)
)
GO
INSERT INTO test VALUES ('19.01');
INSERT INTO test VALUES ('23.41');
ALTER TABLE test ADD data_new decimal(19,6)
GO
UPDATE test SET data_new = CAST(data AS decimal(19,6));
ALTER TABLE test DROP COLUMN data
GO
EXEC sp_RENAME 'test.data_new' , 'data', 'COLUMN'
As people have said, that error doesn't come from nulls, it comes from varchar values that can't be converted to decimal. Most typical reason for this I've found (after checking that the column doesn't contain any logically false values, like non-digit characters or double comma values) is when your varchar values use comma for decimal pointer, as opposed to period.
For instance, if you run the following:
DECLARE #T VARCHAR(256)
SET #T = '5,6'
SELECT #T, CAST(#T AS DEC(32,2))
You will get an error.
Instead:
DECLARE #T VARCHAR(256)
SET #T = '5,6'
-- Let's change the comma to a period
SELECT #T = REPLACE(#T,',','.')
SELECT #T, CAST(#T AS DEC(32,2)) -- Now it works!
Should be easy enough to look if your column has these cases, and run the appropriate update before your ALTER COLUMN, if this is the cause.
You could also just use a similar idea and make a regex search on the column for all values that don't match digit / digit+'.'+digit criteria, but i suck with regex so someone else can help with that. :)
Also, the american system uses weird separators like the number '123100.5', which would appear as '123,100.5', so in those cases you might want to just replace the commas with empty strings and try then?
I'm running a pretty standard
INSERT INTO [table] (col1, col2, ...coln)
select * from #temp
and I'm getting the following error:
Msg 245, Level 16, State 1, Line 1
Conversion failed when converting the varchar value 'NULL' to data type int.
I understand the error, but want to know why the column that is causing issue isn't identified by the error message. Is there an easy way to find which column contains the naughty null or is this just a ploy to make me look like I'm being productive at work while I really just spent 30 minutes looking at a huge result set without getting anywhere?
Edit: Thanks for the help guys, but no one really answered the question. Do all RDBMS's spew out similar error messages are or some more helpful? Its 2012...trial and error over possibly thousands of columns should be dead!
I would look at how you populate the temp table. You appear to be getting a value of 'null' not NULL. If this data is coming from a Excel file, this is a common problem. I usually clease the data first by updating this way:
Update #temp
set field1 = NULL
where field1 = 'NULL'
If you want to do all in the same update command, then
Update #temp
set field1 = NULLIF(field1, 'NULL')
, field2 = NULLIF(field2, 'NULL')
, field3 = NULLIF(field3, 'NULL')
It shouldn't take you 30 minutes to figure out where the null is. You only have so many columns. Just start selecting from #temp WHERE col1 IS NULL, then WHERE col2 is.
If #temp has a VARCHAR column you're trying to put into in INT column then cast it. If there are NULLs you might want to handle them with an CAST(ISNULL(VarCharColumn, '0') AS INT) or something. If an INT column allows NULLS, then just the cast to INT should be enough (as long as all the values are NULL or a valid int).
If you write your INSERT with a little bit more care then you should be able to get the results you want.
You're going to need some trial and error as #Jeremy pointed out. But you can winnow down the choices.
The error message says that the problem is a NULL in a varchar column. You can restrict your searching to just the varchar columns in #temp: select * from #temp where col1 is null or col3 is null
Second, the problem is also happening when the database engine tries to convert a null varchar value to an integer not null. Compare the definitions of both tables to see where a varchar in #temp matches up with an integer not null in the other table.
This, however, is suspicious. Why are you trying to convert text to numbers? If that's what you really want to do, you will probably need an explicit cast from textual to numeric.
If you run these two statements before your query you will see null values on those columns in the results set:
SET ARITHABORT OFF
SET ANSI_WARNINGS OFF