SQLite Persistence project : errorMsg - ios

Question

I use errorMsg in my NSAssert, but I only defined it as NULL and never used it to get the actual error message. So, it will always be NULL and there is no point to use it in NSAssert.
<...>
char *errorMsg = NULL;
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(database, update, -1, &stmt, nil)
== SQLITE_OK) {
sqlite3_bind_int(stmt, 1, i);
sqlite3_bind_text(stmt, 2, [field.text UTF8String], -1, NULL);
}
if (sqlite3_step(stmt) != SQLITE_DONE)
NSAssert(0, #"Error updating table: %s", errorMsg);
<...>
will anyone give a solution?
when I run the app, there is no harm. but then, when I press the home button, the process paused and shows me this:
2013-05-20 23:57:50.156 SQLite Persistence[5373:c07] * Assertion failure in -[LPEViewController applicationWillResignActive:], /Users/Me/Developer/SQLite Persistence/SQLite Persistence/LPEViewController.m:84 2013-05-20 23:57:50.158 SQLite Persistence[5373:c07] Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error updating table: (null)' ** First throw call stack: (0x2094012 0x11a1e7e 0x2093e78 0xc37665 0x3c09 0xc624f9 0x20ee0c5 0x2048efa 0xb96bb2 0xe2bb1 0xe2c3d 0xece0c 0xf5e74 0xf6beb 0xe8698 0x1fefdf9 0x1fefad0 0x2009bf5 0x2009962 0x203abb6 0x2039f44 0x2039e1b 0x1fee7e3 0x1fee668 0xe5ffc 0x2b4d 0x2a75) libc++abi.dylib: terminate called throwing an exception (lldb)

Answer 1

A couple of issues:
You never set the errorMsg. Make sure to set it to sqlite3_errmsg (or just use that function directly).
Your custom error message ("Error updating table") is a little misleading, too, as it would imply that you're reporting the name of a table, whereas your choice of variable name suggested you really wanted to report the SQLite error message.
If sqlite3_prepare_v2 fails, you don't report any error message. Furthermore, rather than stopping and reporting an error if sqlite3_prepare_v2 failed, you proceed to try to call sqlite3_step, even though there's no valid statement to perform. The problem with that is that it would undoubtedly replace the meaningful error message you would have received after sqlite3_prepare_v2 failed with some useless message about executing statements in the wrong order.
You don't check the success or failure of your sqlite3_bind statements. It would be prudent to do so (though I suspect you're more likely to fail at the sqlite3_prepare_v2 statement).
Anyway, maybe you want something like:
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(database, update, -1, &stmt, nil) != SQLITE_OK)
NSAssert(0, #"prepare failure: %s", sqlite3_errmsg(database));
if (sqlite3_bind_int(stmt, 1, i) != SQLITE_OK) {
sqlite3_finalize(stmt);
NSAssert(0, #"bind 1 failure: %s", sqlite3_errmsg(database));
}
if (sqlite3_bind_text(stmt, 2, [field.text UTF8String], -1, NULL) != SQLITE_OK) {
sqlite3_finalize(stmt);
NSAssert(0, #"bind 2 failure: %s", sqlite3_errmsg(database));
if (sqlite3_step(stmt) != SQLITE_DONE) {
sqlite3_finalize(stmt);
NSAssert(#"step error: %s", sqlite3_errmsg(database));
}
sqlite3_finalize(stmt);
Whether you want to use NSAssert or just NSLog and immediately return, I'll defer to you, but this code sample will check more SQLite failure conditions and report meaningful errors.