'unknown error' in SQLite on the iPhone when selecting total number of records
Trying to return whether a record exists in SQLite on the iPhone except I keep getting an 'unknown error'.
selectStmt is static sqlite3_stmt *selectStmt = nil;
used here if(selectStmt) sqlite3_finalize(selectStmt);
which only gets executed if the application terminates. This functionality works fine with delete statements and insert statements so I'm guessing it's something wron开发者_开发问答g with the below logic?
- (BOOL) doesBookExist {
if(selectStmt == nil) {
const char *sql = "select count(*) from books where isbn = ?";
if(sqlite3_prepare_v2(database, sql, -1, &selectStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating select statement. '%s'", sqlite3_errmsg(database));
}
//When binding parameters, index starts from 1 and not zero.
int count = sqlite3_bind_text(selectStmt, 1, [isbn UTF8String], -1, SQLITE_TRANSIENT);
if (SQLITE_DONE != sqlite3_step(selectStmt))
NSAssert1(0, @"Error while selecting. '%s'", sqlite3_errmsg(database));
sqlite3_reset(selectStmt);
return (count > 0);
}
sqlite3_bind_text
returns a success/error code, not the result of any query. And step should return SQLITE_ROW
, since you have one row of result data (regardless of whether the count is 0 or more). There seemed to be an error, because you were expecting SQLITE_DONE
when the correct value was SQLITE_ROW
. Then, to get the count, you need to use sqlite3_column_int
after executing step. So something like:
int bind_res = sqlite3_bind_text(selectStmt, 1, [isbn UTF8String], -1, SQLITE_TRANSIENT);
if (SQLITE_OK != bind_res)
{
// log error, return...
}
// One row of result data, so step should return SQLITE_ROW
if (SQLITE_ROW != sqlite3_step(selectStmt))
{
NSAssert1(0, @"Error while selecting. '%s'", sqlite3_errmsg(database));
// log error, return
}
int count = sqlite3_column_int(selectStmt, 0);
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