sql - How can a substring from a varchar variable be null? -

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sql - How can a substring from a varchar variable be null? -

primarily sql server user suprised in oracle syntax valid:

select var table substr(var, 2, 1) null

how can subsrting varchar string variable null? in sql server never true(?).

select var table substring(var, 2, 1) null

in many cases in oracle, the empty string null.

if substr() outside range of in-string, sql server returns empty string, while oracle returns null (its equivalent empty string).

sql sql-server oracle

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