Query using a derived table with ISNUMERIC results

2019-07-09 02:47发布

Here's an example query:

DECLARE @table table (loc varchar(10))

INSERT INTO @table VALUES
('134a'), ('123'), ('abc'), ('124')

SELECT * 
FROM (
    SELECT * FROM @table WHERE ISNUMERIC(loc) = 1
) as a
WHERE CAST(loc as INT) BETWEEN 100 AND 200

If I have some varchar values and I limit them to numeric values using ISNUMERIC in a derived table in the query, why does it result in a conversion error?:

Conversion failed when converting the varchar value '134a' to data type int.

Is there a way around this?

1条回答
家丑人穷心不美
2楼-- · 2019-07-09 03:17

The WHERE clause executes first. Try:

DECLARE @table table (loc varchar(10)) 

INSERT INTO @table VALUES 
('134a'), ('123'), ('abc'), ('124') 

SELECT *  
FROM ( 
    SELECT * FROM @table
) as a 
WHERE ISNUMERIC(loc) = 1 and CAST(loc as INT) BETWEEN 100 AND 200 
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