Error converting data type varchar to float перевод

Sometimes, under certain circumstances, when you develop in SQL Server and especially when you try to convert a string data type value to a float data type value, you might get the error message: error converting data type varchar to float. As the error message describes, there is a conversion error and this is most probably due to the input parameter value you used in the conversion function.

Read more below on how you can easily resolve this problem.

Reproducing the Data Type Conversion Error

As mentioned above, the actual reason you get this error message, is that you are passing as a parameter to the CAST or CONVERT SQL Server functions, a value (varchar expression) that is invalid and cannot be converted to the desired data type.

Consider the following example:

-----------------------------------------
--Variable declaration and initialization
-----------------------------------------
DECLARE @value AS VARCHAR(50);

SET @value = '12.340.111,91';

--Perform the casting
SELECT CAST(@value AS FLOAT);

--or
--Perform the conversion
SELECT CONVERT(FLOAT, @value);
-----------------------------------------

If you execute the above code you will get an error message in the following type:

Msg 8114, Level 16, State 5, Line 6
Error converting data type varchar to float.

Another similar example where you get the same data type conversion error, is the below:

-----------------------------------------
--Variable declaration and initialization
-----------------------------------------
DECLARE @value2 AS VARCHAR(50);

SET @value2 = '12,340.15';

--Perform the casting
SELECT CAST(@value2 AS FLOAT);

--or
--Perform the conversion
SELECT CONVERT(FLOAT, @value2);

Why you get this Conversion Error

The exact reason for getting the error message in this case is that you are using the comma (,) as a decimal point and also the dots as group digit symbols. Though SQL Server considers as a decimal point the dot (.). Also when converting a varchar to float you must not use any digit grouping symbols.

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How to Resolve the Conversion Issue

In order for the above code to execute, you would need to first remove the dots (that is the digit grouping symbols in this case) and then replace the comma with a dot thus properly defining the decimal symbol for the varchar expression.

Note: You need to be careful at this point, in order to correctly specify the decimal symbol at the correct position of the number.

Therefore, you can modify the code of example 1 as per below example:

-------------------------------------------
--Variable declaration and initialization
-------------------------------------------
DECLARE @value AS VARCHAR(50);

SET @value = '12.340.111,91';

--Prepare the string for casting/conversion to float
SET @value = REPLACE(@value, '.', '');
SET @value = REPLACE(@value, ',', '.');

--Perform the casting
SELECT CAST(@value AS FLOAT);

--or
--Perform the conversion
SELECT CONVERT(FLOAT, @value);
-----------------------------------------

If you execute the above code you will be able to get the string successfully converted to float.

Similarly, you can modify the code of example 2 as per below example:

-----------------------------------------
--Variable declaration and initialization
-----------------------------------------
DECLARE @value2 AS VARCHAR(50);

SET @value2 = '12,340.15';

--Prepare the string for casting/conversion to float
SET @value2 = REPLACE(@value2, ',', '');

--Perform the casting
SELECT CAST(@value2 AS FLOAT);

--or
--Perform the conversion
SELECT CONVERT(FLOAT, @value2);

Again, if you execute the above code you will be able to get the string successfully converted to float.

*Note: Even though you can try changing the regional settings of the PC for setting the dot (.) as the decimal symbol, this will only affect the way the data is presented to you when returned from the casting/conversion call. Therefore, you still have to modify the varchar expression prior to the casting/conversion operation.

Regarding the message: error converting data type varchar to numeric

The above error message is similar to the one we examined in this article, therefore, the way for resolving the issue is similar to the one we described in the article. The only different for the numeric case, is that you will have to replace FLOAT with numeric[ (p[ ,s] )]. Learn more about the numeric data type in SQL Server and how to resolve the above conversion issue, by reading the relevant article on SQLNetHub.

Watch the Live Demonstration on the VARCHAR to FLOAT Data Type Conversion Error

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How to resolve the error: Error converting data type varchar to float

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The issue that you’re having is that you’re specifically searching for strings that contain a % character, and then converting them (implicitly or explicitly) to float.

But strings containing % signs can’t be converted to float whilst they still have a % in them. This also produces an error:

select CONVERT(float,'12.5%')

If you’re wanting to convert to float, you’ll need to remove the % sign first, something like:

CONVERT(float,REPLACE(terms_code,'%',''))

will just eliminate it. I’m not sure if there are any other characters in your terms_code column that may also trip it up.

You also need to be aware that SQL Server can quite aggressively re-order operations and so may attempt the above conversion on other strings in terms_code, even those not containing %. If that’s the source of your error, then you need to prevent this aggressive re-ordering. Provided there are no aggregates involved, a CASE expression can usually avoid the worst of the issues — make sure that all strings that you don’t want to deal with are eliminated by earlier WHEN clauses before you attempt your conversion

The issue that you’re having is that you’re specifically searching for strings that contain a % character, and then converting them (implicitly or explicitly) to float.

But strings containing % signs can’t be converted to float whilst they still have a % in them. This also produces an error:

select CONVERT(float,'12.5%')

If you’re wanting to convert to float, you’ll need to remove the % sign first, something like:

CONVERT(float,REPLACE(terms_code,'%',''))

will just eliminate it. I’m not sure if there are any other characters in your terms_code column that may also trip it up.

You also need to be aware that SQL Server can quite aggressively re-order operations and so may attempt the above conversion on other strings in terms_code, even those not containing %. If that’s the source of your error, then you need to prevent this aggressive re-ordering. Provided there are no aggregates involved, a CASE expression can usually avoid the worst of the issues — make sure that all strings that you don’t want to deal with are eliminated by earlier WHEN clauses before you attempt your conversion

CASE
WHEN (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))> 0 AND (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))<=0.25 THEN (0.25+FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))

WHEN (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))> 0.25 AND (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))<=0.50 THEN (0.50+FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))

WHEN (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))> 0.50 AND (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))<=0.75 THEN (0.75+FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))

WHEN (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))> 0.75 AND (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))<1 THEN (1+FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))


WHEN (Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)- FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))= 0 THEN (0+FLOOR(Cast(CONVERT(DECIMAL(10,2),(totaleffort/7.40)) as nvarchar)))

END

AS Estimated_Effort_Days,

Приведенный выше код в настоящее время округляет поле с именем totaleffort до ближайшего 25, например, если у меня значение 78.19, оно будет округлено до 78.25.

У меня есть новое требование для значения нуля, когда значение = 0, тогда мне нужно отобразить текст «неизвестный номер». Я попытался добавить дополнительный оператор case, однако запрос не выполняется с ошибкой:

Ошибка преобразования типа данных varchar в float.

Есть ли у кого-нибудь рекомендации для меня?

It means you have at least one row in the table that cannot be cast to float. Doing the CASE is safe, but combining the CTE and adding a WHERE clause falls into a common fallacy of programmers when writing T-SQL: that order of declaration implies an order of execution. Programmers are used to the imperative procedural style of C like languages and fail to comprehend the declarative set based nature of SQL. I have wrote before about this issue and gave examples when the fallacy causes errors:

• T-SQL functions do no imply a certain order of execution
• On SQL Server boolean operator short-circuit

Once you post your full code we can see where exactly did you make the fallacy in your case and assumed a certain order of execution.

after update

OK, so I have to admin that in your case the code is correct in the order of execution, the result column cannot be projected w/o first evaluating the CASE. Had the CASE been in a WHERE clause things would have been different.

Your problem is different: ISNUMERIC. This function has a very generous understanding of what NUMERIC means and has bitten many developers before. Namely, it accepts values that CAST and CONVERT will reject. Like ones containing a comma:

declare @n varchar(8000) = '1,000';
select isnumeric(@n);
select cast(@n as float);
select case when isnumeric(@n)=1 then cast(@n as float) else null end;

So you have values that pass the ISNUMERIC test but fail to convert. Just a heads up, the more you’ll digg into this approach, the more closed doors you’ll find. Is just no safe way to do the cast you need on the server side. Ideally, fix the data model (make the field a float if it stores floats). Short of that, triage the data and remove all values that are not a proper float, and fix the front-end/application to no longer introduce new ones, then add a constraint that will trigger the error if new bad values appear. You won’t be able to solve this in a query, that road is littered with bodies.

With the next version of SQL Server you will have a new function, TRY_CONVERT, that would solve your problem.