About the "substr(X,Y,Z)" function, I observe a strange behaviour when Y
= 0.
If I execute this script:
select 'abcd',substr('abcd',0,1),substr('abcd',1,1),substr('abcd',2,1);
select 'abcd',substr('abcd',0,2),substr('abcd',1,2),substr('abcd',2,2);
select 'abcd',substr('abcd',0,9),substr('abcd',1,9),substr('abcd',2,9);
select 'abcd',substr('abcd',0),substr('abcd',1),substr('abcd',2);
It prints:
+--------+--------------------+--------------------+--------------------+
| 'abcd' | substr('abcd',0,1) | substr('abcd',1,1) | substr('abcd',2,1) |
+--------+--------------------+--------------------+--------------------+
| abcd | | a | b |
+--------+--------------------+--------------------+--------------------+
+--------+--------------------+--------------------+--------------------+
| 'abcd' | substr('abcd',0,2) | substr('abcd',1,2) | substr('abcd',2,2) |
+--------+--------------------+--------------------+--------------------+
| abcd | a | ab | bc |
+--------+--------------------+--------------------+--------------------+
+--------+--------------------+--------------------+--------------------+
| 'abcd' | substr('abcd',0,9) | substr('abcd',1,9) | substr('abcd',2,9) |
+--------+--------------------+--------------------+--------------------+
| abcd | abcd | abcd | bcd |
+--------+--------------------+--------------------+--------------------+
+--------+------------------+------------------+------------------+
| 'abcd' | substr('abcd',0) | substr('abcd',1) | substr('abcd',2) |
+--------+------------------+------------------+------------------+
| abcd | abcd | abcd | bcd |
+--------+------------------+------------------+------------------+
It seems that Y=0 denotes a fictitious empty position before the first
one (Y=1).Is it the intended behaviour?
The documentation (https://www.sqlite.org/lang_corefunc.html#substr),
says nothing about this specific pattern.
J-L Hainaut
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