I have a column that is currently set as nvarchar(max) and I want to convert the column to decimal(38,2). The problem I am running into is that a few of the millions of rows are in the format of -1.943E12 and because the E is present I get an error, Cannot convert nvarchar into numeric, when I try to cast the column into a decimal. Is there anyway to do this?
CREATE TABLE practice (cost nvarchar(max))
INSERT INTO practice values ('123'),('44232.99'),('43.4432'),('1.943E12')
SELECT CAST(cost as decimal(32,2)) FROM practice
What I'm ultimately trying to do is insert data from a staging table (where all columns are nvarchar(max)) into a table with appropriate datatypes. I kept getting an error, so after digging through each of the 40 columns, I found 5 columns where this scientific notation occurs. Any advice on how to do this at scale without having to check each column?
INSERT INTO practice_corrected_datatypes
SELECT * FROM practice
Numeric cannot convert from exponential format, but float can. Therefore you could do this by going via float. For example:
print cast(cast('1.943E12' as float) as decimal(38,2))
assuming you have try_parse() and try_cast()
SELECT try_cast(try_parse(cost as float) as decimal(32,2))
FROM practice
The advantage is that they return NULL instead of failing. You could probably get by with just the inner try_parse()
SELECT cast(try_parse(cost as float) as decimal(32,2))
FROM practice
Try this...
update p
set cost = cast(cast(cost as float) as decimal(32,2))
from practice p
where cost like '%E%'
Related
I'm working on Migrating SQL Server data to Snowflake and trying to convert Int to Decimal. But the response is not what I'm expecting.
In SQL If you run this query Select 1.0000 or Select Cast(1 as Decimal(12,4)) the result will 1.000.
If I do the same in Snowflake the result is 1. Is there a way to fix it?
Thanks
You can use
select to_number(1,12,4)
For more info
Select Cast(1 as Decimal(12,4)) the result will 1.000. If I do the same in Snowflake the result is 1. Is there a way to fix it?
Representation of the number does not matter. It is most likely a client tool that shows it without decimal places.
When EXPLICIT cast is involved the data type is set as requested and it could be easily confirmed with DESCRIBE RESULT:
SELECT CAST(1 AS DECIMAL(12,4)) AS col;
DESCRIBE RESULT LAST_QUERY_ID();
-- name type kind null?
-- col NUMBER(12,4) COLUMN Y
DECIMAL and NUMBER are synonyms in Snowflake.
I'm developing a database with SQL Server 2012 SP2.
I have a table with a NVARCHAR(20) column, and it will have numbers: "000001", "000002", etc.
I need to get the greatest value in that column and convert it to int. How can I do it?
I have found that I can convert a nvarchar to int with this sql sentence:
SELECT CAST(YourVarcharCol AS INT) FROM Table
But I don't know how can I get the max value in that column because the numbers are nvarchar.
UPDATE:
By the way, this column is NVARCHAR because I need to store text on it. I'm testing my solution and I need to store ONLY numbers to test it.
If your numbers are padded like in the example given and all have the same width, you can just sort them alphanumerically and then cast the max-value to INT or BIGINT (depending on your numbers range).
If there are very many rows it was much faster, especially if there is an index on this column...
Something like
SELECT TOP 1 * FROM YourTable
ORDER BY NumberColumn DESC
or, if you need the max-value only:
SELECT MAX(NumberColumn) FROM YourTable
If you have to deal with negative numbers or differently padded numbers you have to cast them first
SELECT TOP 1 * FROM YourTable
ORDER BY CAST(NumberColumn AS INT) DESC
or
SELECT MAX(CAST(NumberColumn AS INT)) FROM YourTable
Please note:
If you've got very many rows, the second might get rather slow. Read about sargable
If your NumberColumn might include invalid values, you have to check, Read about ISNUMERIC().
The best solution - in any case - was to use an indexed numeric column to store these values
Try this one...
I think MAX is enough.
SELECT max(CAST(YourVarcharCol AS INT)) FROM Table
Try this
SELECT MAX(t.Y) from (SELECT CAST(YourVarcharCol AS INT) as Y FROM Table) t
You should try this on finding the highest value:
SELECT MAX(CAST(YourVarcharCol AS INT)) AS FROM Table
If all the data follow the same padding and formatting pattern, a simple max(col) would do.
However, if not, you have to cast the values to int first. Searching on a columns cast to some other datatype will not use an index, if there's any, but will scan the whole table instead. It may or may not be OK for you, depending on requirements and number of rows in the table. If performance is what you need, then create a calculated column as try_cast( col as int), and create an index on it.
Note that you should not use cast, but try_cast instead, to guard against values that can't be cast (if you use a datatype to store something which is essencially of another datatype, it always opens up a possibility for errors).
Of couse, if you can change the original column's type to int, it would be the best.
This will return max int value
SELECT MAX(IIF(ISNUMERIC(YourVarcharCol) = 1, YourVarcharCol, '0') * 1) FROM Table
You can use like this
select max(cast(ColumnName AS INT ))from TableName
I've got a field in a table that has a DataType of varchar(10). This field contains numeric values that are formatted as a varchar, for the sole purpose of being used to join two tables together. Some sample data would be:
AcctNum AcctNumChar
2223333 2223333
3324444 3324444
For some records, the table sometimes thinks this field (AcctNumChar) is numeric and the join doesn't work properly. I then have to use an Update statement to re-enter the value as a varchar.
Is there any way to determine whether or not the field has a varchar or numeric value in it, using a query? I'm trying to narrow down which records are faulty without having to wait for one of the users to tell me that their query isn't returning any hits.
You can use isnumeric() for a generic comparison, for instance:
select (case when isnumeric(acctnum) = 1 then cast(acctnum as decimal(10, 0))
end)
In your case, though, you only seem to want integers:
(case when acctnum not like '%[^0-9]%' then cast(acctnum as decimal(10, 0))
end)
However, I would strongly suggest that you update the table to change the data type to a number, which appears to be the correct type for the value. You can also add a computed column as:
alter table t add AcctNum_Number as
(case when acctnum not like '%[^0-9]%' then cast(acctnum as decimal(10, 0))
end)
Then you can use the computed column rather than the character column.
There are several ways to check if varchar column contains numeric value but I recommend to you to us TRY_CONVERT function.
It will give you NULL if the value cannot be converted to number. For example, to get all records that have numeric values, you can do this:
SELECT *
FROM [table]
WHERE TRY_CONVERT(INT, [value]) IS NOT NULL
You can use CAST and CONVERT (Transact-SQL) functions here to solve your purpose.
reference here - https://msdn.microsoft.com/en-IN/library/ms187928.aspx.
IsNumeric worked, TRY_CONVERT didn't (SQL wouldn't recognize it as a built-in function for some reason). Anyway, for the record I ran the following query and got all of my suspect records:
SELECT *
FROM ACCT_LIST
where IsNumeric([ACCT_NUM_CHAR]) = 0
Use PATINDEX function:
DECLARE #s VARCHAR(20) = '123123'
SELECT PATINDEX('%[^0-9]%', #s)
If #s variable will have something different from range 0-9 this function will return the index of first occurence of non digit symbol. If all symbols are digits it will return 0.
I got a sql server error and not sure how to fix it.I got a column 'NAME' in a view 'Products' with a type of nvarchar(30), the query is generated dynamically in code so cannot quite change it.
I got the 'Arithmetic overflow error converting nvarchar to data type numeric.' for the following query:
select * FROM Products WHERE NAME=12.0
however the following query works fine:
select * FROM Products WHERE NAME=112.0
I am quite confused by the error, I know I should put quotes around the number but just want know why the second query works and is there any settings could make the first query work?
update: also
select * FROM Products WHERE NAME=cast('12.0' as decimal(4,2))
doesn't work, but
select * FROM Products WHERE NAME=cast('12.0' as decimal(5,2))
works, any particular reasons?
Many thanks!
SQL Server is trying to convert the values in your table to match the perceived data type of the value coded into your WHERE clause. If you have data values with more numbers (e.g., DECIMAL(5,2)) and you try to convert them to match a value with fewer (e.g., DECIMAL(3,1)), then you will have an overflow.
Consider the following SQL, which will throw an error:
DECLARE #Products TABLE (NAME NVARCHAR(30))
INSERT INTO #Products VALUES ('123.45')
INSERT INTO #Products VALUES ('12.0')
SELECT *
FROM #Products
WHERE NAME = 12.0
Now try this, which will work:
DECLARE #Products TABLE (NAME NVARCHAR(30))
INSERT INTO #Products VALUES ('123.45')
INSERT INTO #Products VALUES ('12.0')
SELECT *
FROM #Products
WHERE NAME = CAST(12.0 AS DECIMAL(5,2))
The difference between these is that SQL Server now accounts for cases where the table contains a number with a higher precision and/or scale than the one specified in the WHERE clause.
EDIT: further reading. Books Online states in the data type definition for DECIMAL and NUMERIC that:
In Transact-SQL statements, a constant with a decimal point is
automatically converted into a numeric data value, using the minimum
precision and scale necessary. For example, the constant 12.345 is
converted into a numeric value with a precision of 5 and a scale of 3.
Therefore, when you issue a query with the constant '12.0', it is being converted to the data type NUMERIC(3,1) and then trying to convert the NVARCHAR value to match.
I currently have a table with a column as varchar. This column can hold numbers or text. During certain queries I treat it as a bigint column (I do a join between it and a column in another table that is bigint)
As long as there were only numbers in this field had no trouble but the minute even one row had text and not numbers in this field I got a "Error converting data type varchar to bigint." error even if in the WHERE part I made sure none of the text fields came up.
To solve this I created a view as follows:
SELECT TOP (100) PERCENT ID, CAST(MyCol AS bigint) AS MyCol
FROM MyTable
WHERE (isnumeric(MyCol) = 1)
But even though the view shows only the rows with numeric values and casts Mycol to bigint I still get a Error converting data type varchar to bigint when running the following query:
SELECT * FROM MyView where mycol=1
When doing queries against the view it shouldn't know what is going on behind it! it should simply see two bigint fields! (see attached image, even mssql management studio shows the view fields as being bigint)
OK. I finally created a view that works:
SELECT TOP (100) PERCENT id, CAST(CASE WHEN IsNumeric(MyCol) = 1 THEN MyCol ELSE NULL END AS bigint) AS MyCol
FROM dbo.MyTable
WHERE (MyCol NOT LIKE '%[^0-9]%')
Thanks to AdaTheDev and CodeByMoonlight. I used your two answers to get to this. (Thanks to the other repliers too of course)
Now when I do joins with other bigint cols or do something like 'SELECT * FROM MyView where mycol=1' it returns the correct result with no errors. My guess is that the CAST in the query itself causes the query optimizer to not look at the original table as Christian Hayter said may be going on with the other views
Ideally, you want to try to avoid storing the data in this form - would be worth splitting the BIGINT data out in to a separate column for both performance and ease of querying.
However, you can do a JOIN like this example. Note, I'm not using ISNUMERIC() to determine if it's a valid BIGINT because that would validate incorrect values which would cause a conversion error (e.g. decimal numbers).
DECLARE #MyTable TABLE (MyCol VARCHAR(20))
DECLARE #OtherTable TABLE (Id BIGINT)
INSERT #MyTable VALUES ('1')
INSERT #MyTable VALUES ('Text')
INSERT #MyTable VALUES ('1 and some text')
INSERT #MyTable VALUES ('1.34')
INSERT #MyTable VALUES ('2')
INSERT #OtherTable VALUES (1)
INSERT #OtherTable VALUES (2)
INSERT #OtherTable VALUES (3)
SELECT *
FROM #MyTable m
JOIN #OtherTable o ON CAST(m.MyCol AS BIGINT) = o.Id
WHERE m.MyCol NOT LIKE '%[^0-9]%'
Update:
The only way I can find to get it to work for having a WHERE clause for a specific integer value without doing another CAST() on the supposedly bigint column in the where clause too, is to use a user defined function:
CREATE FUNCTION [dbo].[fnBigIntRecordsOnly]()
RETURNS #Results TABLE (BigIntCol BIGINT)
AS
BEGIN
INSERT #Results
SELECT CAST(MyCol AS BIGINT)
FROM MyTable
WHERE MyCol NOT LIKE '%[^0-9]%'
RETURN
END
SELECT * FROM [dbo].[fnBigIntRecordsOnly]() WHERE BigIntCol = 1
I don't really think this is a great idea performance wise, but it's a solution
To answer your question about the error message: when you reference a view name in another query (assuming it's a traditional view not a materialised view), SQL Server effectively does a macro replacement of the view definition into the consuming query and then executes that.
The advantage of doing this is that the query optimiser can do a much better job if it sees the whole query, rather than optimising the view separately as a "black box".
A consequence is that if an error occurs, error descriptions may look confusing because the execution engine is accessing the underlying tables for the data, not the view.
I'm not sure how materialised views are treated, but I would imagine that they are treated like tables, since the view data is cached in the database.
Having said that, I agree with previous answers - you should re-think your table design and separate out the text and integer data values into separate columns.
Try changing your view to this :
SELECT TOP 100 PERCENT ID,
Cast(Case When IsNumeric(MyCol) = 1 Then MyCol Else null End AS bigint) AS MyCol
FROM MyTable
WHERE (IsNumeric(MyCol) = 1)
Have you tried to convert other table's bigint field into varchar? As for me it makes sense to perform more robust conversion... It shouldn't affect your performance too much if varchar field is indexed.
Consider creating a redundant bigint field to hold the integer value of af MyCol.
You may then index the new field to speed up the join.
Try using this:
SELECT
ID,
CAST(MyCol AS bigint) as MyCol
FROM
(
SELECT TOP (100) PERCENT
ID,
MyCol
FROM
MyTable
WHERE
(isnumeric(MyCol) = 1)
) as tmp
This should work since the inner select only return numeric values and the outer select can therefore convert all values from the first select into a numeric. It seems that in your own code SQL tries to cast before executing the isnumeric function (maybe it has something to do with optimizing).
Try doing the select in 2 stages.
first create a view that selects all columns where my col is nummeric.
Then do a select in that view where you cast the varchar field.
The other thing you could look at is your design of tables to remove the need for the cast.
EDIT
Are some of the numbers larger than bigint?
Are there any spaces, leading, trailing or in the number?
Are there any format characters? Decimal points?