SQLite3 基本使用方法（一）

#import <UIKit/UIKit.h>
#import <sqlite3.h>

@interface MSViewController : UIViewController
{
    //Sqlite3数据库的链接，基于该链接可以进行数据库操作
    sqlite3 * m_pDb;
}
@end

#import "MSViewController.h"
#import <sqlite3.h>

@interface MSViewController ()

@end

@implementation MSViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    //1. 创建数据库
    [self openDB];
    //2. 创建数据库表
    [self createTable];
    //3. 数据操作
    
    //添加
    //[self addUserWithName:@"YY" pass:@"yy135"];
    
    //查询
    /*
    NSMutableArray * arr =  [self selectAllUser];
    for (int i=0; i<arr.count; i++) {
        NSLog(arr[i]);
    }*/
    
    //修改
    //[self updateUserId:2 name:@"wangxin" pass:@"wangxin000"];
    
    //删
    [self deleteUserId:2];
    
}


///Users/username/Library/Application Support/iPhone Simulator/  "沙盒路径"
//打开数据库，如不存在，则创建。
- (void) openDB
{
    //生成存放在沙盒中的数据库完整路径
    NSString * strDocDir = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString * strDbName = [strDocDir stringByAppendingPathComponent: @"mySqlite3DB.db"];
    
    
    //sqlite3 数据库的链接，基于该链接可以进行数据库操作
    if (SQLITE_OK == sqlite3_open(strDbName.UTF8String, &m_pDb))
    {
        NSLog(@"创建/打开数据库成功！");
    }
    else
    {
        NSLog(@"创建/打开数据库失败！");
    }
}





//创建数据库表
//使用DBMANAGE创建，把生成的代码赋值过来就OK了。
//表名：tbl_User
//IF NOT EXISTS

//IOS 把id设为自增，在添加数据的时候，也要用null站位，不能不写。
- (void) createTable
{
    NSString * strSql = @"CREATE TABLE IF NOT EXISTS tbl_User (Id integer NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,UserName text,UserPass text)";
    
    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, strSql.UTF8String, NULL, NULL, &pErrorMsg)) {
        NSLog(@"创建数据表成功!");
    }
    else
    {
        NSLog(@"创建数据表失败!");
    }
 
}



//增
- (void)addUserWithName:(NSString *)strName pass:(NSString *)strPass
{
    NSString * strSql = [NSString stringWithFormat: @"INSERT INTO tbl_User VALUES (null, ‘%@‘, ‘%@‘)", strName, strPass];
    
    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, strSql.UTF8String, NULL, NULL, &pErrorMsg)) {
        NSLog(@"添加成功!");
    }
    else
    {
        NSLog(@"添加失败!");
    }
}


//查
- (NSMutableArray *) selectAllUser
{
    NSString * strSql = @"SELECT * FROM tbl_User";
    
    NSMutableArray * arrReturn = [NSMutableArray array];
    
    //1. 评估准备SQL语法是否正确
    sqlite3_stmt * pStmt = NULL;
    if (SQLITE_OK == sqlite3_prepare_v2(m_pDb, strSql.UTF8String, -1, &pStmt, NULL))
    {
        NSLog(@"sql语法正确！");
        
        //2. 如果能正常查询，调用单步执行方法， 依次取得查询结果
        //如果得到一行记录
        while (SQLITE_ROW == sqlite3_step(pStmt))
        {
            //3.获取/显示查询结果
            int nId = sqlite3_column_int(pStmt, 0);
            const unsigned char * pUserName = sqlite3_column_text(pStmt, 1);
            NSString * pUserNameUTF8 = [NSString stringWithUTF8String:(const char *)pUserName];
            const unsigned char * pUserPass = sqlite3_column_text(pStmt, 2);
            NSString * pUserPassUTF8 = [NSString stringWithUTF8String:(const char *)pUserPass];
            
            NSString * strTemp = [NSString stringWithFormat:@"%d -- %@ -- %@",nId,pUserNameUTF8, pUserPassUTF8];
            [arrReturn addObject:strTemp];
        }
    }
    else
    {
        NSLog(@"sql语法错误!");
    }
    //4. 释放句柄
    sqlite3_finalize(pStmt);
    
    return arrReturn;
}


//改
- (void) updateUserId:(int)nId name:(NSString *)strUserName pass:(NSString *)strUserPass
{
    NSString * strSql = [NSString stringWithFormat: @"UPDATE tbl_User SET UserName= ‘%@‘, UserPass=‘%@‘ WHERE Id= %d", strUserName, strUserPass, nId];
    
    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, strSql.UTF8String, NULL, NULL, &pErrorMsg)) {
        NSLog(@"添加成功!");
    }
    else
    {
        NSLog(@"添加失败!");
    }
}


//删
- (void) deleteUserId:(int)nId
{
    NSString * strSql = [NSString stringWithFormat: @"delete from tbl_User where Id = %d", nId];
    
    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, strSql.UTF8String, NULL, NULL, &pErrorMsg)) {
        NSLog(@"添加成功!");
    }
    else
    {
        NSLog(@"添加失败!");
    }
}


@end