How to convert nvarchar to numeric in SQL Server

Question

How to convert nvarchar to numeric ?

I got this error:

Error converting data type nvarchar to numeric.

This is my query

SELECT 
    strIpay88Amt, 
    CONVERT(NUMERIC(18, 2), strIpay88Amt) AS iPay
FROM
    tblCurrTrxMaster 

Answer 1

Assuming that there are string values in strIpay88Amt column. You can use following to convert only numeric values.

select cast(strIpay88Amt as numeric) from tblCurrTrxMaster 
where ISNUMERIC(strIpay88Amt) = 1

And following to fetch string values.

select strIpay88Amt from tblCurrTrxMaster where ISNUMERIC(strIpay88Amt) = 0

Answer 2

尝试强制转换语法：

 SELECT strIpay88Amt, CAST(strIpay88Amt AS NUMERIC) AS iPay FROM tblCurrTrxMaster 

Answer 3

There must be some entry in your table that is NOT a valid number and thus your conversion fails - and rightfully so.

So in order to find these entries, you can try this:

SELECT 
    strIpay88Amt, 
    TRY_CONVERT(NUMERIC(18, 2), strIpay88Amt) AS iPay
FROM
    dbo.tblCurrTrxMaster 
WHERE
    TRY_CONVERT(NUMERIC(18, 2), strIpay88Amt) IS NULL

This will use the TRY_CONVERT function to attempt the conversion - and with this WHERE clause, you'll only get back all those entries that could not be converted to a valid NUMERIC .

While NULL will "convert" properly to a numeric, an empty string ( '' ) for instance will already cause an error......