how can i write a query for update data in sql? - ios

Question

Currently, I write query for update data in iOS
NSString *query = [NSString stringWithFormat: #"update *from ericsson_review_form_field_table set value = %# where fieldId = %# and form_index = %d",strFValue,strFieldId,formIndex];
But it is not working.
Please tell me the sql query for update value.

Answer 1

Here you made a mistake in writing query to update any record, just try it
NSString *updateSQL = [NSString stringWithFormat:#"UPDATE EMPLOYEES set name = '%#', department = '%#', age = '%#' WHERE id = ?",
employee.name,
employee.department,
[NSString stringWithFormat:#"%d", employee.age]];

Answer 2

First Google and then ask..See below example for update
UPDATE table_name
SET column1 = value1
WHERE [condition];
UPDATE CUSTOMERS
SET ADDRESS = 'Pune', SALARY = 1000.00;
NSString *updateSQL = [NSString stringWithFormat:#"update table_name SET name='%#' where regno='1000'"];
Hope it helps you....

Answer 3

Simple way to update record in table is as bellow
UPDATE table2
SET table2.col1 = table1.col1,
table2.col2 = table1.col2,
...
FROM table1, table2
WHERE table1.memberid = table2.memberid

Answer 4

Currently my code is
- (BOOL)updateReviewFields:(NSString *)strFieldId andFormIndex:(int)formIndex withFValue:(NSString *)strFValue{
sqlite3_stmt *statement = nil;
NSString *query;
if(sqlite3_open([[appDelegate databasePath] UTF8String],&database) == SQLITE_OK){
query = [NSString stringWithFormat: #"update ericsson_review_form_field_table set value = %# where fieldId = %# and form_index = %d",strFValue,strFieldId,formIndex];
if(sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, NULL)
== SQLITE_OK){
sqlite3_bind_text(statement, 1, [strFieldId UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(statement, 13, [strFValue UTF8String], -1, SQLITE_TRANSIENT);
if(sqlite3_step(statement))
return YES;
else
return NO;
}
sqlite3_finalize(statement);
}
sqlite3_close(database);
return NO;
}
and now it is working fine.

Answer 5

You posted a code sample:
- (BOOL)updateReviewFields:(NSString *)strFieldId andFormIndex:(int)formIndex withFValue:(NSString *)strFValue{
sqlite3_stmt *statement = nil;
NSString *query;
if(sqlite3_open([[appDelegate databasePath] UTF8String],&database) == SQLITE_OK){
query = [NSString stringWithFormat: #"update ericsson_review_form_field_table set value = %# where fieldId = %# and form_index = %d",strFValue,strFieldId,formIndex];
if(sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, NULL)
== SQLITE_OK){
sqlite3_bind_text(statement, 1, [strFieldId UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_text(statement, 13, [strFValue UTF8String], -1, SQLITE_TRANSIENT);
if(sqlite3_step(statement))
return YES;
else
return NO;
}
sqlite3_finalize(statement);
}
sqlite3_close(database);
return NO;
}
I don't see how the above could possibly work.
You're using sqlite3_bind_text, but you don't have any ? placeholders in your SQL to bind to. (You should check the return code from your sqlite3_bind_text calls and I'd be shocked if they're returning SQLITE_OK.)
You're binding the first item and the thirteenth item. The latter bind call, to the thirteenth ?, certainly wouldn't work unless you had at least thirteen ? placeholders.
You're returning immediately after calling sqlite3_step, never hitting your sqlite3_finalize statement and you'd undoubtedly leak memory as a result. You'd also never close the database if you got to these return statements after sqlite3_step.
You're testing if (sqlite3_step(...)). That doesn't make sense, because sqlite3_step always returns a non-zero value (either SQLITE_DONE upon success or some non-zero error code on error).
I'd suggest logging sqlite3_errmsg if any of the SQLite calls fail.
I might suggest changing the return value of the method to be the number of rows that were updated. This way, you can differentiate between (a) successful update; (b) no rows updated (but no errors); and (c) a failure. I might return negative value on error, zero if no rows matched the WHERE criteria, and a positive value, n, if n rows were successfully updated. I use sqlite3_changes to determine how many rows were updated.
Finally, I'd seriously advise against using stringWithFormat to build your SQL (at least if the string values include any user-provided input, because you expose yourself to quoting and/or SQL injection problems).
So, instead, I'd suggest:
/** Update fields
*
* #param strFieldId The fieldId column string value
* #param formIndex The form_index integer value
* #param strFValue The string to which the `value` column should be updated.
*
* #return Returns the number of rows updated. Return negative value on failure. Return zero if no rows matched the WHERE criteria.
*/
- (int)updateReviewFields:(NSString *)strFieldId andFormIndex:(int)formIndex withFValue:(NSString *)strFValue {
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
sqlite3 *database;
NSString *databasePath = [appDelegate databasePath];
sqlite3_stmt *statement = nil;
int rowCount = -1;
int rc;
if ((rc = sqlite3_open([databasePath UTF8String], &database)) != SQLITE_OK) {
NSLog(#"Unable to open database: %# (%ld)", databasePath, (long)rc);
return rowCount;
}
const char *query = "update ericsson_review_form_field_table set value = ? where fieldId = ? and form_index = ?";
if ((rc = sqlite3_prepare(database, query, -1, &statement, NULL)) != SQLITE_OK) {
NSLog(#"sqlite3_prepare fail: %s (%ld)", sqlite3_errmsg(database), (long)rc);
sqlite3_close(database);
return rowCount;
}
if ((rc = sqlite3_bind_text(statement, 1, [strFValue UTF8String], -1, NULL)) != SQLITE_OK) {
NSLog(#"sqlite3_bind_text 1 fail: %s (%ld)", sqlite3_errmsg(database), (long)rc);
} else if ((rc = sqlite3_bind_text(statement, 2, [strFieldId UTF8String], -1, NULL)) != SQLITE_OK) {
NSLog(#"sqlite3_bind_text 2 fail: %s (%ld)", sqlite3_errmsg(database), (long)rc);
} else if ((rc = sqlite3_bind_int(statement, 3, formIndex)) != SQLITE_OK) {
NSLog(#"sqlite3_bind_int 3 fail: %s (%ld)", sqlite3_errmsg(database), (long)rc);
} else if ((rc = sqlite3_step(statement)) != SQLITE_DONE) {
NSLog(#"sqlite3_step fail: %s (%ld)", sqlite3_errmsg(database), (long)rc);
} else {
rowCount = sqlite3_changes(database);
}
sqlite3_finalize(statement);
sqlite3_close(database);
return rowCount;
}