Question

I’m getting data from a mysql database using the C api. I can log the data so I know the query is working fine but I need to take it and put it into a dictionary and The Google is not being helpful with that. Can anyone give me a pointer, snippet or link to get me going in the right direction?

- (IBAction)dbConnect:(id)sender {


NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
MYSQL mysql;
mysql_init(&mysql);

if (!mysql_real_connect(&mysql, "10.1.1.99", "*******", "********", "oldphotoarchive", 0, NULL, 0)) {
    NSLog(@"%@", [NSString stringWithUTF8String:mysql_error(&mysql)]);
} else { 

    MYSQL_RES *result;
    MYSQL_ROW row;
    unsigned int num_fields;
    unsigned int num_rows;
    unsigned long *lengths;

    if (mysql_query(&mysql,"SELECT * FROM photorecord")) {
        // error
    } else { // query succeeded, process any data returned by it  

        result = mysql_store_result(&mysql);
        if (result)  {
            num_fields = mysql_num_fields(result);
            while ((row = mysql_fetch_row(result))) {
                lengths = mysql_fetch_lengths(result);

                lengths = mysql_fetch_lengths(result);
                for(int i = 0; i < num_fields; i++) {
                    printf("[%.*s] ", (int) lengths[i],  row[i] ? row[i] : "NULL");

                    if (row[i]) { 
                                                    //AT THIS POINT I WANT TO DO THE CONVERSION, THIS ISN'T WORKING, INCOMPATIBLE POINTER TYPE
                        NSArray* thisRow = [[NSArray alloc] initWithString: row[i]];
                    }
                }
                printf("\n");

            }


        } else  {// mysql_store_result() returned nothing; should it have?
            if (mysql_errno(&mysql)) {
                NSLog(@ "Error: %s\n", mysql_error(&mysql));
            } else if (mysql_field_count(&mysql) == 0) {
                // query does not return data
                // (it was not a SELECT)
                num_rows = mysql_affected_rows(&mysql);
            }
        }

    }

}

[pool release];
}

Here’s the revised code in case other folks are running into the same wall. Feel free to critique:

#import "AppController.h"

#include "mysql.h"
#include "unistd.h"


@implementation AppController
- (IBAction)dbConnect:(id)sender {


NSMutableDictionary* results = [[NSMutableDictionary alloc] init];

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
MYSQL mysql;
mysql_init(&mysql);

if (!mysql_real_connect(&mysql, "10.1.1.99", "mysqladmin", "m3r!0n", "oldphotoarchive", 0, NULL, 0)) {
    NSLog(@"%@", [NSString stringWithUTF8String:mysql_error(&mysql)]);
} else { 

    MYSQL_RES *result;
    MYSQL_ROW row;
    unsigned int num_fields;
    unsigned int num_rows;
    //unsigned long *lengths;

    NSString* itemID = [[NSString alloc] init];

    if (mysql_query(&mysql,"SELECT * FROM photorecord WHERE logNum > 10000")) {
        // error
    } else { // query succeeded, process any data returned by it  

        result = mysql_store_result(&mysql);
        if (result)  {
            num_fields = mysql_num_fields(result);

            while ((row = mysql_fetch_row(result))) {

                NSMutableDictionary* tmpDict = [[NSMutableDictionary alloc] init];

                for(int i = 0; i < num_fields; i++) {
                    if (row[i]) { 
                        char* cString = row[i];
                        NSString* dataString  = [NSString stringWithCString:cString encoding:NSUTF8StringEncoding];
                        if ([dataString isNotEqualTo: @"NULL"]) { 
                            //NSLog(@"%@", dataString);

                            if (i==0) { 
                                itemID = dataString;
                            }

                            [tmpDict setObject: dataString forKey: [NSString stringWithFormat: @"item_%i", i] ];
                        }
                    }
                }

                [results setObject:tmpDict forKey:itemID];
                NSLog(@"%@", results);

            }

        } else  {// mysql_store_result() returned nothing; should it have?
            if (mysql_errno(&mysql)) {
                NSLog(@ "Error: %s\n", mysql_error(&mysql));
            } else if (mysql_field_count(&mysql) == 0) {
                // query does not return data
                // (it was not a SELECT)
                num_rows = mysql_affected_rows(&mysql);
            }
        }

    }

}


[pool release];

}
@end

You have to do a small bit of set up in order to get MySQL to work in your project:

1. Copy the two framework files libmysqlclient.a and libmysqlclient_r.a (should be in /usr/local/mysql/lib) to your project (place them in the frameworks group/folder). Include all sub folders or whatever that message is when you copy stuff in to a project.

2. Expand Targets, right click and then select Add->Add New Build Phase->New Copy Files Build Phase. Change destination to frameworks. This puts the two frameworks into the build of your project.

3. Copy the /usr/local/mysql/include folder to your project. These are the MySQL header files.

Answer 1

NSArray doesn’t have a ‘initWithString’ method. .

Probably what you want is something like this…

NSString *s = [NSString alloc] initWithBytes: row[i] length: strlen(row[i]) encoding: DefaultCstring]