2015.9.29-数据存取（SQLite）

//
//  DbManager.h
//  DataAccess
//
//  Created by Kenshin Cui on 14-3-29.
//  Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <sqlite3.h>
#import "KCSingleton.h"

@interface KCDbManager : NSObject

singleton_interface(KCDbManager);

#pragma mark - 属性
#pragma mark 数据库引用，使用它进行数据库操作
@property (nonatomic) sqlite3 *database;


#pragma mark - 共有方法
/**
 *  打开数据库
 *
 *  @param dbname 数据库名称
 */
-(void)openDb:(NSString *)dbname;

/**
 *  执行无返回值的sql
 *
 *  @param sql sql语句
 */
-(void)executeNonQuery:(NSString *)sql;

/**
 *  执行有返回值的sql
 *
 *  @param sql sql语句
 *
 *  @return 查询结果
 */
-(NSArray *)executeQuery:(NSString *)sql;
@end

//
//  DbManager.m
//  DataAccess
//
//  Created by Kenshin Cui on 14-3-29.
//  Copyright (c) 2014年 Kenshin Cui. All rights reserved.
//

#import "KCDbManager.h"
#import <sqlite3.h>
#import "KCSingleton.h"
#import "KCAppConfig.h"

#ifndef kDatabaseName

#define kDatabaseName @"myDatabase.db"

#endif

@interface KCDbManager()
@end

@implementation KCDbManager

singleton_implementation(KCDbManager)

#pragma mark 重写初始化方法
-(instancetype)init{
    KCDbManager *manager;
    if((manager=[super init]))
    {
        [manager openDb:kDatabaseName];
    }
    return manager;
}

-(void)openDb:(NSString *)dbname{
    //取得数据库保存路径，通常保存沙盒Documents目录
    NSString *directory=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSLog(@"%@",directory);
    NSString *filePath=[directory stringByAppendingPathComponent:dbname];
    //如果有数据库则直接打开，否则创建并打开（注意filePath是ObjC中的字符串，需要转化为C语言字符串类型）
    if (SQLITE_OK ==sqlite3_open(filePath.UTF8String, &_database)) {
        NSLog(@"数据库打开成功!");
    }else{
        NSLog(@"数据库打开失败!");
    }
}

-(void)executeNonQuery:(NSString *)sql{
    char *error;
    //单步执行sql语句，用于插入、修改、删除
    if (SQLITE_OK!=sqlite3_exec(_database, sql.UTF8String, NULL, NULL,&error)) {
        NSLog(@"执行SQL语句过程中发生错误！错误信息：%s",error);
    }
}

-(NSArray *)executeQuery:(NSString *)sql{
    NSMutableArray *rows=[NSMutableArray array];//数据行
    
    //评估语法正确性
    sqlite3_stmt *stmt;
    //检查语法正确性
    if (SQLITE_OK==sqlite3_prepare_v2(_database, sql.UTF8String, -1, &stmt, NULL)) {
        //单步执行sql语句
int columnCount= sqlite3_column_count(stmt);

            while (SQLITE_ROW==sqlite3_step(stmt)) {
            NSMutableDictionary *dic=[NSMutableDictionary dictionary];
            for (int i=0; i<columnCount; i++) {
                const char *name= sqlite3_column_name(stmt, i);//取得列名
                const unsigned char *value= sqlite3_column_text(stmt, i);//取得某列的值
                dic[[NSString stringWithUTF8String:name]]=[NSString stringWithUTF8String:(const char *)value];
            }
            [rows addObject:dic];
        }
    }
    
    //释放句柄
    sqlite3_finalize(stmt);    
    return rows;
}

//取得数据库保存路径，通常保存沙盒Documents目录(这一步是取沙盒目录)
    NSString *directory=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //传入数据库名字字符串得到数据库地址
    NSString *filePath=[directory stringByAppendingPathComponent:dbname];
//如果有数据库则直接打开，否则创建并打开（注意filePath是ObjC中的字符串，需要转化为C语言字符串类型）
    sqlite3_open(filePath.UTF8String, &_database)

sqlite3_exec(_database, sql.UTF8String, NULL, NULL,&error)

 NSMutableArray *rows=[NSMutableArray array];//数据行

  //评估语法正确性
    sqlite3_stmt *stmt;

//检查语法正确性
    if (SQLITE_OK==sqlite3_prepare_v2(_database, sql.UTF8String, -1, &stmt, NULL))

while (SQLITE_ROW==sqlite3_step(stmt))

while (SQLITE_ROW==sqlite3_step(stmt)) {
            NSMutableDictionary *dic=[NSMutableDictionary dictionary];
            for (int i=0; i<columnCount; i++) {
                const char *name= sqlite3_column_name(stmt, i);//取得列名
                const unsigned char *value= sqlite3_column_text(stmt, i);//取得某列的值
                dic[[NSString stringWithUTF8String:name]]=[NSString stringWithUTF8String:(const char *)value];
            }
            [rows addObject:dic];