sql - Oracle - Sorting a VARCHAR2 field like a NUMBER - I found a solution, need explanation on it -

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i have varchar2 column want sort numerically. 99% (or possibly 100%) of time contain numbers. looking around , found this solution. quoting source:

remember our goal sort supplier_id field in ascending order (based on numeric value). this, try using lpad function.

for example,

select * supplier order lpad(supplier_id, 10);

this sql pads front of supplier_id field spaces 10 characters. now, results should sorted numerically in ascending order.

i've played around little bit solution , seems workign (so far), how work, can explain?

when sorting strings/varchar, field serted left right, sort normal words.

that why have problems when sorting

1 2 3 10 11 20

which sorted as

1 10 11 2 20 3

but, if pad values left, have like

001 002 003 010 011 020

which sort correctly


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