Related to constraint violations, an error message returned by
sqlite3_errmsg() changes to the better after calling sqlite3_reset() or
sqlite3_finalize().
Example code is below, here is the output:
sqlite3_step: 19 constraint failed
sqlite3_reset: 19 t.c may not be NULL
sqlite3_finalize: 0 t.c may not be NULL
As can be seen, sqlite3_reset() "enhances" the error message returned by
sqlite3_errmsg() by filling in the column name and reason why the
constraint failed.
I would like to ask if this could be changed so that sqlite3_step() by
itself generates the more meaningful error message, even without calling
sqlite3_reset() or sqlite3_finalize()?
IIRC, having sqlite3_step() generate the "final" error codes and
messages was one of the reasons that brought about sqlite3_prepare_v2().
I observe that the error message generated after sqlite3_prepare_v2()
("constraint failed") is far better than that of sqlite3_prepare() ("SQL
logic error or missing database"), but it is not as good as it gets
after resetting the statement.
Ralf
---- Example code:
int main(int argc, char* argv[])
{
sqlite3* db;
sqlite3_stmt* stmt;
int e;
sqlite3_open("test.db3", &db);
sqlite3_exec(db, "create table if not exists t (c text not null)",
NULL, NULL, NULL);
sqlite3_prepare_v2 (db, "insert into t values (null)", -1,
&stmt, NULL);
e = sqlite3_step(stmt);
printf("sqlite3_step: %d %s\n", e, sqlite3_errmsg(db));
e = sqlite3_reset(stmt);
printf("sqlite3_reset: %d %s\n", e, sqlite3_errmsg(db));
e = sqlite3_finalize(stmt);
printf("sqlite3_finalize: %d %s\n", e, sqlite3_errmsg(db));
sqlite3_close (db);
printf ("\nDone");
scanf ("*%s");
return 0;
}
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