Can I pass a number for varchar2 in Oracle?

Question

I have an Oracle table and a column (col1) has type varchar2(12 byte). It has one row and value of col1 is 1234

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Answer 1

Oracle says invalid number. Why is that? Why I cannot pass a number when it is varchar2?

Oracle does an implicit conversion from character type of col1 to number, since you're comparing it as a number.

Also, you assume that 1234 is the only row that's being fetched. In reality, Oracle has to fetch all rows from the table, and then filter out as per the where clause. Now there's a character value in col1 that's being fetched before it encounters your 1234 row & that's causing the error, since the character cannot be converted to a number.

This fiddle shows the behaviour. Since abc canot be converted to a number, you get that error message

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Now if the only record in the table is that of col1 containing a numeric character, you'll see that the statement will work fine