Question: How do I handle this conversion if the value is null, so that it does not give the error "Error converting data type varchar to numeric".

```
convert(numeric(19,2), mdmaster.check_no)as checkNbr,

```

Thanx

Answer: 
You can use `ISNULL`:

```
convert(numeric(19,2), ISNULL(mdmaster.check_no, 0))as checkNbr,

```

This will make any `NULL` value be converted to `0.00`.

[Here is a Live Demo](https://data.stackexchange.com/stackoverflow/query/edit/81974)
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You can use ISNUMERIC it will return 0.00 if null

```
DECLARE @t VARCHAR(50);
SELECT convert(numeric(19,2), ISNUMERIC (@t))as checkNbr

```

or you can use approach as shown below if it matchs your requirement in ms sql server

```
SELECT 
    CASE 
        WHEN Field NOT LIKE '%[^0-9]%'
        THEN CAST(Field AS INT)
        ELSE NULL 
    END

```