The SQL you gave translates to
"Change the 'Name' field to have the value 'test' in all records where the 'ID'
field has the value 2".
If there is no such record, then SQL has nothing to do and very successfully
does exactly nothing.
SQL is "set oriented" and update operations on empty sets always succeed.
I guess you are thinking along procedural/file oriented lines as in pseudocode
record.id = 2;
error = readwithlock( file, byID, &record );
if (error) raise exception;
record.name = 'test';
error = updatewithunlock ( file, &record );
if (error) raise exception;
SQLite implements UPDATE as a SELECT followed by REPLACE statemenst as if
written like
(INSERT OR) REPLACE INTO table SELECT id,'test' FROM table WHERE id = 2;
Which is equivalent to (naïve, not using index) pseudocode like
open( file );
while (! eof( file ) )
{
error = readseqwithlock( file, &record );
if (error) raise exception;
if (record.id == 2)
{
record.name = 'test';
error = updatewithunlock( file, &record );
if (error) raise exception;
} else {
error = unlock( file );
if (error) raise exception;
}
}
HTH
Gunter
-----Ursprüngliche Nachricht-----
Von: techi eth [mailto:techi...@gmail.com]
Gesendet: Freitag, 02. August 2013 10:15
An: General Discussion of SQLite Database
Betreff: [sqlite] Where Clause
Come across one issue with conditional query execution.
Query: UPDATE COMPANY SET Name= 'test' WHERE ID = 2; According to my
understanding if no ID = 2 is present in table then error should return but it
return with SQLITE_OK however Name value is not changed.
Cheers -
Techi
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