![]() Note how ISNUMERIC knows these are numbers: SELECT CAST(ExampleColumn AS DECIMAL(13,6)) The below example populates data that we could normally use the CAST(ExampleColumn AS DECIMAL(22,8)) for converting to a numerical column, and these example values look no different than these rare character values the difference is that in the latter case, the casting will fail. This is part of what can create a puzzle for developers - characters which clearly are numbers, not converting or casting as decimals and failing the ISNUMERIC function (which is not always reliable, but will generally see numbers like 1.00 as valid). These rare values will always be decimal characters, with a range of length post decimal point, and will not read as numbers in both C# or PowerShell, even though they are if you were to copy them in a tool like Excel or Google Spreadsheets and run a mathematical function on them (like SUM or AVG). We would not, however, expect to get this error on the second value (1.000000), yet these data will be formatted this way, which is why developers can become confused as to why clear decimal values aren't converting. ![]() In the below five examples, we expect to receive the error "Error converting data type varchar to numeric" on three of these due to characters that aren't convertible to decimals. In other cases, when converting VARCHARs to numerical data points, we can use these other functions to solve the problem. ![]() What differs about these data, compared to other times when facing issues with converting numerical VARCHARs to numerical data points is that all of them will fail the ISNUMERIC (for verifying), CAST, CONVERT, TRY_CONVERT and TRY_PARSE functions (the latter two returning NULLs). We seldom stumble on these types of data, but they can create encumbrances for developers, so it's good to know a work-around when transforming these VARCHARs into numerical data points. Trimming function works to remove the error.
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