iOS FMDB操作sqlite数据库
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一、简单说明
1.什么是FMDB
FMDB是iOS平台的SQLite数据库框架
FMDB以OC的方式封装了SQLite的C语言API
对比苹果自带的Core Data框架,更加轻量级和灵活
提供了多线程安全的数据库操作方法,有效地防止数据混乱
(1)FMDatabase
一个FMDatabase对象就代表一个单独的SQLite数据库
用来执行SQL语句
(2)FMResultSet
使用FMDatabase执行查询后的结果集
(3)FMDatabaseQueue
用于在多线程中执行多个查询或更新,它是线程安全的
FMDatabase *db = [FMDatabase databaseWithPath:path];
if (![db open]) {
NSLog(@"数据库打开失败!");
}
文件路径有三种情况
(1)具体文件路径
如果不存在会自动创建
(2)空字符串@""
会在临时目录创建一个空的数据库
当FMDatabase连接关闭时,数据库文件也被删除
(3)nil
会创建一个内存中临时数据库,当FMDatabase连接关闭时,数据库会被销毁
create、drop、insert、update、delete等
使用executeUpdate:方法执行更新
- (BOOL)executeUpdate:(NSString*)sql, ...
- (BOOL)executeUpdateWithFormat:(NSString*)format, ...
- (BOOL)executeUpdate:(NSString*)sql withArgumentsInArray:(NSArray *)arguments
示例
[db executeUpdate:@"UPDATE t_student SET age = ? WHERE name = ?;", @20, @"Jack"]
- (FMResultSet *)executeQuery:(NSString*)sql, ...
- (FMResultSet *)executeQueryWithFormat:(NSString*)format, ...
- (FMResultSet *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)arguments
示例
// 查询数据
FMResultSet *rs = [db executeQuery:@"SELECT * FROM t_student"];
// 遍历结果集
while ([rs next]) {
NSString *name = [rs stringForColumn:@"name"];
int age = [rs intForColumn:@"age"];
double score = [rs doubleForColumn:@"score"];
1.什么是FMDB
FMDB是iOS平台的SQLite数据库框架
FMDB以OC的方式封装了SQLite的C语言API
2.FMDB的优点
使用起来更加面向对象,省去了很多麻烦、冗余的C语言代码对比苹果自带的Core Data框架,更加轻量级和灵活
提供了多线程安全的数据库操作方法,有效地防止数据混乱
3.FMDB的github地址
https://github.com/ccgus/fmdb二、核心类
FMDB有三个主要的类(1)FMDatabase
一个FMDatabase对象就代表一个单独的SQLite数据库
用来执行SQL语句
(2)FMResultSet
使用FMDatabase执行查询后的结果集
(3)FMDatabaseQueue
用于在多线程中执行多个查询或更新,它是线程安全的
三、打开数据库
通过指定SQLite数据库文件路径来创建FMDatabase对象FMDatabase *db = [FMDatabase databaseWithPath:path];
if (![db open]) {
NSLog(@"数据库打开失败!");
}
文件路径有三种情况
(1)具体文件路径
如果不存在会自动创建
(2)空字符串@""
会在临时目录创建一个空的数据库
当FMDatabase连接关闭时,数据库文件也被删除
(3)nil
会创建一个内存中临时数据库,当FMDatabase连接关闭时,数据库会被销毁
四、执行更新
在FMDB中,除查询以外的所有操作,都称为“更新”create、drop、insert、update、delete等
使用executeUpdate:方法执行更新
- (BOOL)executeUpdate:(NSString*)sql, ...
- (BOOL)executeUpdateWithFormat:(NSString*)format, ...
- (BOOL)executeUpdate:(NSString*)sql withArgumentsInArray:(NSArray *)arguments
示例
[db executeUpdate:@"UPDATE t_student SET age = ? WHERE name = ?;", @20, @"Jack"]
五、执行查询
查询方法- (FMResultSet *)executeQuery:(NSString*)sql, ...
- (FMResultSet *)executeQueryWithFormat:(NSString*)format, ...
- (FMResultSet *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)arguments
示例
// 查询数据
FMResultSet *rs = [db executeQuery:@"SELECT * FROM t_student"];
// 遍历结果集
while ([rs next]) {
NSString *name = [rs stringForColumn:@"name"];
int age = [rs intForColumn:@"age"];
double score = [rs doubleForColumn:@"score"];
}
六、实战
(1)首先将github下载的fmdb文件夹中的文件添加到项目中,并添加libsqlite3.tbd的库引用,如下图
如果没有添加libsqlite3.tbd的话,会报如下错误
主要代码如下
//// ViewController.m// FMDBDemo//// Created by 555chy on 6/22/16.// Copyright © 2016 555chy. All rights reserved.//#import "ViewController.h"#import "fmdb/FMDB.h"#import "fmdb/FMDatabaseAdditions.h"@interface ViewController ()@property FMDatabase *db;@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. /* typedef NS_ENUM(NSUInteger, NSSearchPathDirectory) { NSApplicationDirectory = 1, // supported applications (Applications) NSDemoApplicationDirectory, // unsupported applications, demonstration versions (Demos) NSDeveloperApplicationDirectory, // developer applications (Developer/Applications). DEPRECATED - there is no one single Developer directory. NSAdminApplicationDirectory, // system and network administration applications (Administration) NSLibraryDirectory, // various documentation, support, and configuration files, resources (Library) NSDeveloperDirectory, // developer resources (Developer) DEPRECATED - there is no one single Developer directory. NSUserDirectory, // user home directories (Users) NSDocumentationDirectory, // documentation (Documentation) NSDocumentDirectory, // documents (Documents) NSCoreServiceDirectory, // location of CoreServices directory (System/Library/CoreServices) NSAutosavedInformationDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 11, // location of autosaved documents (Documents/Autosaved) NSDesktopDirectory = 12, // location of user's desktop NSCachesDirectory = 13, // location of discardable cache files (Library/Caches) NSApplicationSupportDirectory = 14, // location of application support files (plug-ins, etc) (Library/Application Support) NSDownloadsDirectory NS_ENUM_AVAILABLE(10_5, 2_0) = 15, // location of the user's "Downloads" directory NSInputMethodsDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 16, // input methods (Library/Input Methods) NSMoviesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 17, // location of user's Movies directory (~/Movies) NSMusicDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 18, // location of user's Music directory (~/Music) NSPicturesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 19, // location of user's Pictures directory (~/Pictures) NSPrinterDescriptionDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 20, // location of system's PPDs directory (Library/Printers/PPDs) NSSharedPublicDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 21, // location of user's Public sharing directory (~/Public) NSPreferencePanesDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 22, // location of the PreferencePanes directory for use with System Preferences (Library/PreferencePanes) NSApplicationScriptsDirectory NS_ENUM_AVAILABLE(10_8, NA) = 23, // location of the user scripts folder for the calling application (~/Library/Application Scripts/code-signing-id) NSItemReplacementDirectory NS_ENUM_AVAILABLE(10_6, 4_0) = 99, // For use with NSFileManager's URLForDirectory:inDomain:appropriateForURL:create:error: NSAllApplicationsDirectory = 100, // all directories where applications can occur NSAllLibrariesDirectory = 101, // all directories where resources can occur NSTrashDirectory NS_ENUM_AVAILABLE(10_8, NA) = 102 // location of Trash directory }; NSSearchPathForDirectoriesInDomains一般情况下只会获得到一个目录,为了兼容多个的情况,所以返回数组 */ NSString *parentPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject]; NSString *dbPath = [parentPath stringByAppendingPathComponent:@"person.sqlite"]; /* 文件路径有3种情况 (1)具体文件路径(如果不存在会自动创建) (2)空字符串@“”(会在临时目录创建一个空的数据库,当FMDatabase连接关闭时,数据库文件也被删除) (3)nil(会创建一个内存中临时数据库,当FMDatabase连接关闭时。数据库也会被销毁) */ FMDatabase *db = [FMDatabase databaseWithPath:dbPath]; if([db open]) { NSLog(@"database open success"); /* sqlite中的基本数据类型 (1)NULL,值是NULL (2)INTEGER,值是有符号整形,根据值的大小以1,2,3,4,5,6或8字节存放 (3)REAL,值是浮点型值,以8字节IEEE浮点数存放 (4)TEXT,值是文本字符串,使用数据库编码(UTF-8,UTF-16BE或者UTF-16LE)存放 (5)BLOB,值是一个数据块,完全按照输入存放 */ bool result = [db executeUpdate:@"CREATE TABLE IF NOT EXISTS PersonTable (id integer PRIMARY KEY AUTOINCREMENT, name text NOT NULL, age integer NOT NULL, money float NOT NULL);"]; if(result) { NSLog(@"create table success"); } else { NSLog(@"create table fail"); } } else { NSLog(@"database open fail"); } self.db = db;}-(void)insert { for(int i=0; i<3; i++) { NSString *name = [NSString stringWithFormat:@"chy_%d", arc4random_uniform(100)]; int age = arc4random_uniform(100); float money = arc4random_uniform(100)/10.0f; BOOL result; //@()是将变量转化为id类型 result = [self.db executeUpdate:@"INSERT INTO PersonTable (name, age, money) VALUES (?,?,?);", name, @(age), @(money)]; NSLog(@"insert method 1 %@", result?@"success":@"fail"); result = [self.db executeUpdate:@"INSERT INTO PersonTable (name, age, money) VALUES (?,?,?);" withArgumentsInArray:@[name, @(age), @(money)]]; NSLog(@"insert method 2 %@", result?@"success":@"fail"); result = [self.db executeUpdateWithFormat:@"INSERT INTO PersonTable (name, age, money) VALUES (%@,%d,%f);", name, age, money]; NSLog(@"insert method 3 %@", result?@"success":@"fail"); }}-(void)delete { /* 在FMDB中,除查询以外的所有炒作,都称为“更新” create、drop、insert、update、delete等 */ BOOL result; result = [self.db executeUpdate:@"DELETE FROM PersonTable;"]; NSLog(@"delete %@", result?@"success":@"fail"); result = [self.db executeUpdate:@"DROP TABLE IF EXISTS PersonTable;"]; NSLog(@"drop %@", result?@"success":@"fail");}-(void)query { int count = [self.db intForQuery:@"SELECT count(*) FROM PersonTable"]; NSLog(@"query count = %d", count); FMResultSet *resultSet = [self.db executeQuery:@"SELECT * FROM PersonTable"]; while([resultSet next]) { int ID = [resultSet intForColumn:@"id"]; NSString *name = [resultSet stringForColumn:@"name"]; int age = [resultSet intForColumn:@"age"]; double money = [resultSet doubleForColumn:@"money"]; NSLog(@"query %d,%@,%d,%lf", ID, name, age, money); }}/* touch的响应链。首先,接收touch事件的必须是用户可交互的View,也就是userInteractionEnabled属性必须是yes 事件传递的规则是:如果上层的view截获事件,那么这个view下面的view就接收不到事件,否则触摸事件就会逐层往下传递 */-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event { [self insert]; [self query]; [self delete];}- (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.}@end
七、运行结果
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