ios FMDB初体验之增删改查

又又好久没见了。想你们。今天写一篇关于fmdb的使用文章。在工作中，我们有时会用到数据库，所以你会需要一个好用的工具。长话短说开始进入正题。

先导入fmdb库文件。还有就是加入libsqlite3.dylib。这2个前期准备好后，我们就可以开工了。

#import "ViewController.h"
#import "FMDB.h"  //导入头文件
@interface ViewController ()

@property(nonatomic,retain) FMDatabaseQueue *fmQueue;//添加一个队列属性

@end

@implementation ViewController

//你数据库的路径
-(FMDatabaseQueue *)fmQueue
{

    if (_fmQueue== nil) {
        NSString *dbPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/student.sqlite"];

        _fmQueue = [FMDatabaseQueue databaseQueueWithPath:dbPath];

        NSLog(@"%@",dbPath);
    }

    return _fmQueue;

}

- (void)viewDidLoad {
    [super viewDidLoad];

    [self createAllBtn];

    //这是在一个代码块中
    [self.fmQueue inDatabase:^(FMDatabase *db) {

        //创建一个表
     [db executeUpdate:@"create table if not exists t_student (id integer primary key autoincrement, name text not null, age integer)"];
        //保持数据库开启
        if (![db open]) {

            return ;
        }
    }];

}

-(void)createAllBtn
{

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];

    btn.frame = CGRectMake(100, 50, 100, 50);
    [btn setTitle:@"增加数据" forState:UIControlStateNormal];

    [btn setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [btn addTarget:self action:@selector(increaseAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];

    UIButton *btn1 = [UIButton buttonWithType:UIButtonTypeSystem];

    btn1.frame = CGRectMake(100, 100, 100, 50);
    [btn1 setTitle:@"删除数据" forState:UIControlStateNormal];

    [btn1 setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [btn1 addTarget:self action:@selector(deleteAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn1];

    UIButton *btn2 = [UIButton buttonWithType:UIButtonTypeSystem];

    btn2.frame = CGRectMake(100, 150, 100, 50);
    [btn2 setTitle:@"修改数据" forState:UIControlStateNormal];

    [btn2 setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [btn2 addTarget:self action:@selector(modifyAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn2];

    UIButton *btn3 = [UIButton buttonWithType:UIButtonTypeSystem];

    btn3.frame = CGRectMake(100, 200, 100, 50);
    [btn3 setTitle:@"查询数据" forState:UIControlStateNormal];

    [btn3 setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [btn3 addTarget:self action:@selector(searchAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn3];

}

-(void)increaseAction:(UIButton *)btn
{

    NSLog(@"增加数据");

    [self.fmQueue inDatabase:^(FMDatabase *db) {

        for (int i = 0; i<100; i++) {

            NSString *name = [NSString stringWithFormat:@"james"];

            int age = 10;

            [db executeUpdate:@"insert into t_student (name,age) values (?,?)",name,[NSNumber numberWithInt:age]];

        }

    }];

}

-(void)deleteAction:(UIButton *)btn
{

    NSLog(@"删除数据");

    [self.fmQueue inDatabase:^(FMDatabase *db) {

        NSString *name = [NSString stringWithFormat:@"james"];

        //注意下这样是不能删除指定数据的，一定要是字符串nsstring类型
        //[db executeUpdate:@"delete from t_student where name = '%@'",name];
        //也就是这样
        NSString *sql = [NSString stringWithFormat:@"delete from t_student where name = '%@'",name];
        [db executeUpdate:sql];

    }];

}

-(void)modifyAction:(UIButton *)btn
{

    NSLog(@"修改数据");

    [self.fmQueue inDatabase:^(FMDatabase *db) {
        NSString *name = [NSString stringWithFormat:@"wq"];

        NSString *set = [NSString stringWithFormat:@"UPDATE  t_student SET name = '%@'",name];
        [db executeUpdate:set];

    }];

}

-(void)searchAction:(UIButton *)btn
{

    NSLog(@"查询数据");

[self.fmQueue inDatabase:^(FMDatabase *db) {

    NSString *sql = [NSString stringWithFormat:@"SELECT *from t_student"];
    FMResultSet *set = [db executeQuery:sql];

    while ([set next])
    {
        int stuId = [set intForColumn:@"id"];
        NSString *name = [set stringForColumn:@"name"];
        int age = [set intForColumn:@"age"];

        NSLog(@"stuId = %d, name = %@, age = %d", stuId, name, age);

        //这里的textview用于显示查询到的数据
        UITextView *text = [[UITextView alloc]init];
        text.frame = CGRectMake(50, 300, 300, 200);
        text.backgroundColor = [UIColor grayColor];

        [text setText:name];
        [self.view addSubview:text];

    }

}];

}

@end

没错就是这样，很简单，大家可以拉到工程中运行下。