标签：
对于iOS工程师有一道常考的面试题，即iOS数据存储的方式
标答如下：
Plist（NSArray\NSDictionary）
Preference (偏好设置\NSUserDefaults)
NSCoding(NSKeyed Archiver\NSkeyedUnarchiver)
SQLite3
Core Data
今天就跟大家分享一下，SQLite3的基础知识
什么是SQLite
SQLite 是一款轻型的嵌入式关系型数据库，
它速度要强于Mysql，PostgreSQL，而且占用资源少，在嵌入式设备中可能只需要几百K的内存。
下面是创建该数据库的demo（备注我们需要导入libsqlite3.0.tbd的库）
#import "ViewController.h" #import <sqlite3.h> @interface ViewController () @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; NSString *filename=[[NSSearchPathForDirectoriesInDomains(13, 1, 1)lastObject]stringByAppendingPathComponent:@"newsqlite.sqlite"]; // Do any additional setup after loading the view, typically from a nib. sqlite3 *database=nil; //打开数据库,如果数据库不存在就创建 if( sqlite3_open(filename.UTF8String,&database)==SQLITE_OK) { NSLog(@"打开成功"); /** * 如果存在就无需创建 */ char *errmsg; NSString *sql=@"create table if not exists t_student(id integer primary key autoincrement,name text,age integer);"; sqlite3_exec(database, sql.UTF8String, NULL, NULL, &errmsg); if(errmsg) { NSLog(@"创建表失败"); }else{NSLog(@"创建表成功"); } /** * 关闭数据库 */ sqlite3_close(database); } else{ NSLog(@"打开数据库失败"); } } @end
为了简便，我们把获取沙盒路径封装的类别里代码如下
NSString+Tool.h #import <Foundation/Foundation.h> @interface NSString (Tool) +(NSString * )cachaPathName:(NSString *)fileName; @end NSString+Tool.m #import "NSString+Tool.h" @implementation NSString (Tool) +(NSString * )cachaPathName:(NSString *)fileName{ return [[NSSearchPathForDirectoriesInDomains(13, 1, 1) lastObject] stringByAppendingPathComponent:fileName]; } @end
然后我们来实现一下，数据库中的增删改查四种操作
用故事板拖四个按钮分别是增删改查，在按钮的方法实现中实现对表的增删改查
#import "ViewController.h" #import <sqlite3.h> #import "NSString+Tool.h" static sqlite3 * dataBase = nil; @interface ViewController () @property (nonatomic ,copy) NSString * filename; @end @implementation ViewController - (IBAction)selectAction:(id)sender { //1.打开数据库 if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) { //2.执行查询语句 //准备查询 NSString * sql = @"select * from t_sss;"; //查询句柄 sqlite3_stmt * stmt; if (sqlite3_prepare(dataBase, sql.UTF8String, -1, &stmt, NULL) == SQLITE_OK) { //查询数据 while (sqlite3_step(stmt) == SQLITE_ROW) { //获取表数据的内容 NSString * name = [NSString stringWithCString:(const char *)sqlite3_column_text(stmt, 1) encoding:NSUTF8StringEncoding]; NSLog(@"name = %@",name); NSUInteger age = sqlite3_column_int(stmt, 2); NSLog(@"age = %zd",age); } } //3.关闭数据库 sqlite3_close(dataBase); } } - (IBAction)insertAction:(id)sender { //1.打开数据库 if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) { //2.执行插入语句 for (int i = 0; i < 100; i ++) { NSString * sql =[NSString stringWithFormat: @"insert into t_sss (name,age) values (‘%@‘,%zd);",@"别昱枢",arc4random_uniform(100)]; char * errmsg; sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg); if (errmsg) { NSLog(@"插入失败"); }else{ NSLog(@"插入成功"); } //3.关闭数据库 sqlite3_close(dataBase); } } } - (IBAction)deleteAction:(id)sender { //1.打开数据库 if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) { //2.执行插入语句 for (int i = 0; i < 100; i ++) { NSString * sql =@"delete from t_sss where name = ‘gaga‘;"; char * errmsg; sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg); if (errmsg) { NSLog(@"删除失败"); }else{ NSLog(@"删除成功"); } //3.关闭数据库 sqlite3_close(dataBase); } } } - (IBAction)updateAction:(id)sender { //1.打开数据库 if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) { //2.执行更新语句 for (int i = 0; i < 100; i ++) { NSString * sql =@"update t_sss set name = ‘gaga‘ where age > 50;"; char * errmsg; sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg); if (errmsg) { NSLog(@"更新失败"); }else{ NSLog(@"更新成功"); } //3.关闭数据库 sqlite3_close(dataBase); } } } - (void)viewDidLoad { [super viewDidLoad]; NSString * filename = [NSString cachaPathName:@"sss.sqlite"]; self.filename = filename; NSLog(@"%@",filename); //操作sqlite3 //打开数据库，如果不存在就创建 //arg1:数据库的沙盒存放地址 //arg2:数据库的地址，也可以叫句柄 if (sqlite3_open(filename.UTF8String, &dataBase) == SQLITE_OK) { NSLog(@"数据库打开成功"); //建表,如果存在表就不建 NSString * sql = @"create table if not exists t_sss (id integer primary key autoincrement , name text, age integer);"; //执行数据库语句 char * errmsg; sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL,&errmsg); if (errmsg) { NSLog(@"创建表失败"); }else{ NSLog(@"创建表成功"); } //关闭数据库 sqlite3_close(dataBase); }else{ NSLog(@"数据库打开失败"); } } @end
细心的同学可以看出增删改的操作相似，所以我们封装一下
SqliteManager.h #import <Foundation/Foundation.h> @interface SqliteManager : NSObject +(BOOL) sqlite3WithSql :(NSString *)sql; @end SqliteManager.m #import "SqliteManager.h" #import "NSString+Tool.h" #import <sqlite3.h> static sqlite3 * dataBase = nil; @interface BYSSqliteManager () @property (nonatomic ,copy) NSString * filename; @end @implementation BYSSqliteManager +(BOOL) sqlite3WithSql :(NSString *)sql{ return NO; } +(void)initialize{ NSString * filename = [NSString cachaPathName:@"sss.sqlite"]; NSLog(@"%@",filename); //操作sqlite3 //打开数据库，如果不存在就创建 //arg1:数据库的沙盒存放地址 //arg2:数据库的地址，也可以叫句柄 if (sqlite3_open(filename.UTF8String, &dataBase) == SQLITE_OK) { NSLog(@"数据库打开成功"); //建表,如果存在表就不建 NSString * sql = @"create table if not exists t_sss (id integer primary key autoincrement , name text, age integer);"; //执行数据库语句 char * errmsg; sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL,&errmsg); if (errmsg) { NSLog(@"创建表失败"); }else{ NSLog(@"创建表成功"); } //关闭数据库 sqlite3_close(dataBase); }else{ NSLog(@"数据库打开失败"); } } @end
标签：
原文地址：http://www.cnblogs.com/iOSlearner/p/5474795.html
