问题
I would like to update some data in Xcode sqlite db. The db is successfully connected, but seems like there's something wrong in the sql statement, it keeps returning "Failed to add contact", thanks for helping.
- (void) saveData:(id)sender
{
NSLog(@"The code runs through here!");
sqlite3_stmt *statement;
NSString *documents = [self applicationDocumentsDirectory];
NSString *dbPath = [documents stringByAppendingPathComponent:@"monitorDB.sqlite"];
const char *dbpath = [dbPath cStringUsingEncoding:NSASCIIStringEncoding];
if (sqlite3_open(dbpath, & contactDB) == SQLITE_OK)
{
NSString *insertSQL = [NSString stringWithFormat:
@"UPDATE profile SET username = \"%@\" WHERE id = 1" ,
self.username.text];
const char *insert_stmt = [insertSQL UTF8String];
sqlite3_prepare_v2(contactDB, insert_stmt,
-1, &statement, NULL);
if (sqlite3_step(statement) == SQLITE_DONE)
{
self.settingStatus.text = @"Contact added";
} else {
self.settingStatus.text = @"Failed to add contact";
}
sqlite3_finalize(statement);
sqlite3_close(contactDB);
} else {
self.settingStatus.text = @"DB Not Connect";
}
}
回答1:
Try like this..
In viewdidload we need to check wether table exist or not. If not we need to create db.
NSString *docsdir;
NSArray *dirpaths;
dirpaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsdir=[dirpaths objectAtIndex:0];
dabasePath=[NSString stringWithFormat:[docsdir stringByAppendingPathComponent:@"contact.db"]];
NSFileManager *filemgr= [NSFileManager defaultManager];
if ([filemgr fileExistsAtPath:dabasePath]==NO ) {
const char *dbpath=[dabasePath UTF8String];
if (sqlite3_open(dbpath, &contactDB)== SQLITE_OK) {
char *error;
const char *sql_stmt="CREATE TABLE IF NOT EXISTS CONTACTS (ID INTEGER PRIMARY KEY AUTOINCREMENT, ADDRESS TEXT, NAME TEXT, PHONE TEXT, IMAGE BLOB)";
if (sqlite3_exec(contactDB, sql_stmt, NULL, NULL, &error)!= SQLITE_OK) {
status.text=@"failed to create";
}
sqlite3_close(contactDB);
}
}
To save data try to use the following code.
-(IBAction)saveData:(id)sender{
sqlite3_stmt *statement;
const char *dbpath = [dabasePath UTF8String];
NSData *imagedata=UIImagePNGRepresentation(imageview.image);
if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK) {
NSString *insertSql =[NSString stringWithFormat:@"INSERT INTO CONTACTS (name, address, phone, image) VALUES (\"%@\", \"%@\", \"%@\", ?) ", name.text, address.text, phone.text ];
// NSString *nam=name.text;
const char *insert_stmt = [insertSql UTF8String];
sqlite3_prepare_v2(contactDB, insert_stmt, -1, &statement, NULL);
sqlite3_bind_blob(statement, 1, [imagedata bytes], [imagedata length], NULL);
if (sqlite3_step(statement) == SQLITE_DONE) {
status.text=@"contact added";
[self clearClick:nil];
}else{
status.text=@"failed to added";
}
sqlite3_finalize(statement);
sqlite3_close(contactDB);
}
}
To update data try to use the following code.
-(IBAction)updateClick:(id)sender{
sqlite3_stmt *updateStmt;
const char *dbpath = [dabasePath UTF8String];
if(sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
{
const char *sql = "update contacts Set address = ?, phone = ?, image = ? Where name=?";
if(sqlite3_prepare_v2(contactDB, sql, -1, &updateStmt, NULL)==SQLITE_OK){
sqlite3_bind_text(updateStmt, 4, [name.text UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(updateStmt, 1, [address.text UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(updateStmt, 2, [phone.text UTF8String], -1, SQLITE_TRANSIENT);
NSData *imagedata=UIImagePNGRepresentation(imageview.image);
sqlite3_bind_blob(updateStmt, 3, [imagedata bytes], [imagedata length], NULL);
}
}
char* errmsg;
sqlite3_exec(contactDB, "COMMIT", NULL, NULL, &errmsg);
if(SQLITE_DONE != sqlite3_step(updateStmt)){
NSLog(@"Error while updating. %s", sqlite3_errmsg(contactDB));
}
else{
[self clearClick:nil];
}
sqlite3_finalize(updateStmt);
sqlite3_close(contactDB);
}
回答2:
Check your sql query and change it like this.
NSString *insertSQL = [NSString stringWithFormat:
@"UPDATE profile SET username = '%@' WHERE id = 1" ,
self.username.text];
Or if you want to do using bind text.
if (sqlite3_open(dbpath, & contactDB) == SQLITE_OK)
{
const char *insert_stmt = "UPDATE profile SET username = ? WHERE id = 1";
if(sqlite3_prepare_v2(contactDB, insert_stmt,
-1, &statement, NULL)== SQLITE_OK)
{
sqlite3_bind_text(statement, 1, [self.username.text UTF8String], -1, SQLITE_TRANSIENT);
}
if (sqlite3_step(statement) == SQLITE_DONE)
{
self.settingStatus.text = @"Contact added";
} else {
self.settingStatus.text = @"Failed to add contact";
}
sqlite3_finalize(statement);
sqlite3_close(contactDB);
} else {
self.settingStatus.text = @"DB Not Connect";
}
回答3:
Just check
in .h file NSString *databaseName;
NSString *databasePath;
and in .m file specify databaseName = @"Db name";
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [documentPaths objectAtIndex:0];
databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
-(void)save:(id)sender
{
[self checkAndCreateDatabase];
sqlite3 *contactDB;
sqlite3_stmt *updateStmt;
if(sqlite3_open([databasePath UTF8String], &contactDB) == SQLITE_OK)
{
NSString *querySql=[NSString stringWithFormat:
@"UPDATE profile SET username = \"%@\" WHERE id = 1" ,
self.username.text];
const char*sql=[querySql UTF8String];
if(sqlite3_prepare_v2(contactDB,sql, -1, &updateStmt, NULL) == SQLITE_OK)
{
if(SQLITE_DONE != sqlite3_step(updateStmt))
{
NSLog(@"Error while updating. '%s'", sqlite3_errmsg(contactDB));
}
else{
sqlite3_reset(updateStmt);
NSLog(@"Update done successfully!");
}
}
sqlite3_finalize(updateStmt);
}
sqlite3_close(contactDB);
}
-(void) checkAndCreateDatabase{
BOOL success;
NSFileManager *fileManager = [NSFileManager defaultManager];
success = [fileManager fileExistsAtPath:databasePath];
if(success) return;
NSString *databasePathFromApp = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:databaseName];
[fileManager copyItemAtPath:databasePathFromApp toPath:databasePath error:nil];
}
回答4:
There are many possibilities check all of the below:
1) Initialize statement with nil
sqlite3_stmt *statement = nil;
2) Try below
if (sqlite3_prepare_v2(contactDB, insert_stmt,-1, &statement, NULL) == SQLITE_OK)
{
while (sqlite3_step(statement) == SQLITE_ROW)
{
//Updated
}
}
else
{
NSLog(@"error is %s",sqlite3_errmsg(database));
}
回答5:
Are you sure the dbPath is not in app bundle? We can't update db in the bundle.
sqlite3_prepare_v2() and sqlite3_step() will return an int.
You can find something you want in sqlite3.h.
Like #define SQLITE_BUSY 5 /* The database file is locked */ ...
And, why not use FMDB? You can find it easy on Github. (Link https://github.com/ccgus/fmdb )
来源：https://stackoverflow.com/questions/18713462/ios-using-sqlite-database-update-data-not-working