学步园

1.新建一个View－based Application项目。

2.右击项目中Frameworks文件夹，在其中添加libsqlite3.dylib库。

3.在.h头文件中声明一个类型为sqlite3的变量以及一个获取Documents文件夹下数据库文件目录的方法：

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

@interface SQLiteDataBase : UIViewController {
    sqlite3 *db;//数据库对象
}

-(NSString *)getDocumentsPath;//获取Documents文件夹路径

@end

4.在.m文件中实现头文件中声明的getDocumentsPath方法：

//获取Documents文件夹中文件路径
-(NSString *)getDocumentsPath{
    NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString * documentsdir = [paths objectAtIndex:0];
    return  [documentsdir stringByAppendingPathComponent:@"database.sql"];
}

5.创建并打开数据库，在.m文件中添加如下方法：

//创建打开数据库
-(void) openDB{
    if (sqlite3_open([[self getDocumentsPath] UTF8String], &db)!=SQLITE_OK) {
        sqlite3_close(db);
        NSAssert(0, @"数据库打开失败");//停止应用程序并关闭数据库连接
    }
}

6.创建表，在.m文件中添加如下方法：

//创建表
-(void)createTableNamed:(NSString *) tableName withFiled1:(NSString *) field1 withField2:(NSString *)field2{
    char *err;
    NSString *sql = [NSString stringWithFormat:@"CREATE TABLE IF  NOT EXISTS '%@' ('%@' TEXT PRIMARY KEY, '%@' TEXT);",tableName,field1,field2];//创建表的sql语句
    if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, &err)!=SQLITE_OK) {
        sqlite3_close(db);
        NSAssert(0, @"表创建失败");
    }
}

7.插入记录，在.m文件中添加如下方法：

//插入记录
-(void)insertRecordIntoTableNamed:(NSString *)tableName 
                withField1:(NSString *)field1
                field1Value:(NSString *)field1Value
                addField2:(NSString *)field2
                field2Value:(NSString *)field2Value{
    //第一种方法，对于非查询SQL语句，最好使用这种方法
    NSString *sql = [NSString stringWithFormat:@"INSERT OR REPLACE INTO '%@' ('%@','%@') VALUES ('%@','%@')",tableName,field1,field2,field1Value,field2Value];
    char *err;
    if (sqlite3_exec(db, [sql UTF8String], NULL, NULL, &err)!=SQLITE_OK) {
        sqlite3_close(db);
        NSAssert(0, @"插入记录失败");
    }
    
    //下面是另外一种方法
//    NSString *sqltwo = [NSString stringWithFormat:@"INSERT OR REPLACE INTO '%@'('%@','%@') VALUES(?,?)",tableName,field1,field2];
//    const char *sql = [sqltwo UTF8String];
//    sqlite3_stmt *statement;
//    if (sqlite3_prepare_v2(db, sql, -1, &statement, nil)==SQLITE_OK) {
//        sqlite3_bind_text(statement, 1,  [field1Value UTF8String], -1,NULL);
//        sqlite3_bind_text(statement, 2,  [field2Value UTF8String], -1,NULL);
//    }
//    
//    if (sqlite3_step(statement)!=SQLITE_DONE) {
//        NSAssert(0, @"插入记录失败");
//        sqlite3_finalize(statement);
//    }
}

8.查询记录，在.m文件中添加如下方法：

//查询记录
-(void)getAllRowsFromTableNamed:(NSString *)tableName{
    NSString *qsql = [NSString stringWithFormat:@"SELECT * FROM %@",tableName];
    sqlite3_stmt *statement;
    if (sqlite3_prepare_v2(db, [qsql UTF8String], -1, &statement, nil)==SQLITE_OK) {
        while (sqlite3_step(statement)== SQLITE_ROW) {
            
            char *field1 = (char *)sqlite3_column_text(statement, 0);
            NSString *field1Str = [[NSString alloc]initWithUTF8String:field1];
            
            char *field2 = (char *)sqlite3_column_text(statement, 1);
            NSString *field2Str = [[NSString alloc]initWithUTF8String:field2];
            
            NSString *str = [[NSString alloc]initWithFormat:@"username:%@,password:%@",field1Str,field2Str];
            NSLog(@"%@",str);
            
            [field1Str release];
            [field2Str release];
            [str release];
            
        }
        sqlite3_finalize(statement);
    }
           
}

9.最后在viewDidLoad方法里面添加如下代码，调用各个方法，使得一进入这个页面就可以看到打印出来的结果（运行结果在本文最后）：

- (void)viewDidLoad
{
    //创建数据库
    [self openDB];
    //创建表
    [self createTableNamed:@"Login" withFiled1:@"username" withField2:@"password"];
    //插入记录
    for(int i = 0;i<=2;i++){
        NSString *username = [[NSString alloc]initWithFormat:@"helijun%d",i];
         NSString *password = [[NSString alloc]initWithFormat:@"ameng%d",i];
        [self insertRecordIntoTableNamed:@"Login" withField1:@"username" field1Value:username addField2:@"password" field2Value:password];
        [username release];
        [password release];
    }
    //查询记录并打印出来
    [self getAllRowsFromTableNamed:@"Login"];
    //关闭数据库
    sqlite3_close(db);
    
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

运行结果：