数据库

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1. 创建一个继承于NSObject的类 : DataBaseHandler

DataBaseHandler.h中

{

sqlite3 * dbPoint;//指针指向的是本地数据库文件

}

//作为一个数据处理的类,其对象最好为一个单例

+ (DataBaseHandler *)shareInstance;

//开启数据库

- (void)openDB;

//关闭数据库

- (void)closeDB;

//创建表

- (BOOL)creatTable;

//插入数据

- (BOOL)insertTableWithName:(NSString *)name age:(int)age number:(int)number;

//删除数据

- (BOOL)deleteTableWithName:(NSString *)name;

//更新数据

- (BOOL)updateName:(NSString *)scorceName toName:(NSString *)targetName;

//查询数据

- (NSArray *)selectTable;

DataBaseHandler.m

+ (DataBaseHandler *)shareInstance

{

static DataBaseHandler * handler= nil;

//保证线程安全的情况下进行一次

static dispatch_once_t onceToken;

dispatch_once(&onceToken, ^{

handler = [[DataBaseHandleralloc] init];

//第一次执行的时候打开数据库创建单例

[handler openDB];

});

return handler;

}

#warning //开启数据库

- (void)openDB

{

//1.拼接一个数据库文件的地址

NSArray * arrPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);

//沙盒中的documents文件夹

NSString * documentPath = [arrPathlastObject];

NSLog(@"%@",documentPath);

//拼接处地址

NSString * dbPointPath = [documentPathstringByAppendingPathComponent:@"lanou.db"];

NSLog(@"%@",dbPointPath);

//参数1:数据库的文件路径

//参数2: sqlite3指针的地址&dbPoint 属性

//[dbPointPath UTF8String] 将NSString转成constchar *类型

int result = sqlite3_open([dbPointPath UTF8String], &dbPoint);

//对数据库结果进行判断

if (result == SQLITE_OK) {

NSLog(@"打开成功");

}

else

{

NSLog(@"打开失败");

}

- (void)closeDB

{

int result = sqlite3_close(dbPoint);

if (result == SQLITE_OK) {

NSLog(@"关闭数据库成功");

}else

{

NSLog(@"关闭数据库失败");

}

- (BOOL)creatTable

{

//注意两个单引号

NSString * sqlStr = [NSStringstringWithFormat:@"create tableStudent (name text,age int,number int primary key)"];

char * error = nil;

int result = sqlite3_exec(dbPoint, [sqlStr UTF8String], NULL, NULL, &error);

if (result == SQLITE_DONE) {

return YES;

}

return NO;

//1.数据库的替身缓冲地带确保更新完成之后会自动的更新数据库

//作用 :存储所有对数据库的修改

sqlite3_stmt * stmt = nil;

//2.检查SQL语句,为执行sql语句做的准备

//参数1:数据库指针

//参数2:SQL语句不需要@ 直接双引号里面填写

//参数3:限制sql语句的长度不想限制长度写-1

//参数4:数据库替身stmt的地址

int result =sqlite3_prepare(dbPoint,"create table Student (name text,ageint,number int primary key)", -1, &stmt,nil);

//3.判断检查的结果

if (result == SQLITE_OK) {

//4.执行sql语句

int sqlResult = sqlite3_step(stmt);

//判断sqlResult

if (sqlResult == SQLITE_DONE ) {

//stmt 数据保存到数据库指针释放掉

sqlite3_finalize(stmt);

return YES;

}

//如果检查sql语句失败,将stmt指针释放掉

sqlite3_finalize(stmt);

return NO;

}

#warning //插入

- (BOOL)insertTableWithName:(NSString *)name age:(int)age number:(int)number

{

//注意两个单引号

NSString * sqlStr = [NSStringstringWithFormat:@"insert into Studentvalues ('%@',%d,%d)",name,age,number];

char * error = nil;

int result = sqlite3_exec(dbPoint, [sqlStr UTF8String], NULL, NULL, &error);

if (result == SQLITE_DONE) {

return YES;

}

return NO;

//1.替身

sqlite3_stmt * stmt = nil;

//注意NULL

int result =sqlite3_prepare(dbPoint,"insert into Student values(?,?,?)", -1, &stmt,NULL);

//3.给问号 ?绑定参数和数据

//参数1 :替身

//参数2 :给哪个位置的 ?绑定第一个元素为1

//参数3:提供的数据

sqlite3_bind_text(stmt, 1, [name UTF8String], -1,NULL);

sqlite3_bind_int(stmt, 2, age);

sqlite3_bind_int(stmt, 3, number);

//4.sql检查无误

if (result == SQLITE_OK) {

//5.执行

if (sqlite3_step(stmt) ==SQLITE_DONE) {

//6.释放

sqlite3_finalize(stmt);

return YES;

}

sqlite3_finalize(stmt);

return NO;

}

#warning //更新

- (BOOL)updateName:(NSString *)scorceName toName:(NSString *)targetName

{

//注意两个单引号

NSString * sqlStr = [NSStringstringWithFormat:@"update Student setname = '%@' where name = '%@'",scorceName,targetName];

char * error = nil;

int result = sqlite3_exec(dbPoint, [sqlStr UTF8String], NULL, NULL, &error);

if (result == SQLITE_DONE) {

return YES;

}

return NO;

//1.替身

sqlite3_stmt * stmt = nil;

//注意NULL

int result =sqlite3_prepare(dbPoint,"update Student set name = ? wherename = ?", -1, &stmt,NULL);

//3.给问号 ?绑定参数和数据

//参数1 :替身

//参数2 :给哪个位置的 ?绑定第一个元素为1

//参数3:提供的数据

sqlite3_bind_text(stmt, 1, [scorceName UTF8String], -1,NULL);

sqlite3_bind_text(stmt, 2, [targetName UTF8String], -1,NULL);

//4.sql检查无误

if (result == SQLITE_OK) {

//5.执行

if (sqlite3_step(stmt) ==SQLITE_DONE) {

//6.释放

sqlite3_finalize(stmt);

return YES;

}

sqlite3_finalize(stmt);

return NO;

}

#warning 删除改进除了查询之外的方法都可以简化

- (BOOL)deleteTableWithName:(NSString *)name

{

//注意两个单引号

NSString * sqlStr = [NSStringstringWithFormat:@"delete from Studentwhere name = '%@'",name];

char * error = nil;

int result = sqlite3_exec(dbPoint, [sqlStr UTF8String], NULL, NULL, &error);

if (result == SQLITE_DONE) {

return YES;

}

return NO;

#warning 原来的复杂算法

sqlite3_stmt * stmt = nil;

int result =sqlite3_prepare(dbPoint,"delete from Student where name =?", -1, &stmt,NULL);

sqlite3_bind_text(stmt, 1, [name UTF8String ], -1,NULL);

//4.Sql检查无误

if (result == SQLITE_OK) {

//5.执行

if (sqlite3_step(stmt) ==SQLITE_DONE) {

//6.保存/释放

sqlite3_finalize(stmt);

return YES;

}

sqlite3_finalize(stmt);

return NO;

}

#warning //查询显示所有的

- (NSArray *)selectTable

{

sqlite3_stmt * stmt = nil;

int result = sqlite3_prepare(dbPoint, "select * fromStudent", -1, &stmt, NULL);

if (result == SQLITE_OK) {

//数组用来存储结果

NSMutableArray * arr = [NSMutableArrayarray];

while (sqlite3_step(stmt) ==SQLITE_ROW)

{

//获取每行的数据

const unsigned char * nameChar = sqlite3_column_text(stmt, 0);

NSString * name = [NSStringstringWithUTF8String:(constchar *)nameChar];//产生第一条数据

int age = sqlite3_column_int(stmt, 1);

int number = sqlite3_column_int(stmt, 2);

NSString * str = [NSStringstringWithFormat:@"姓名:%@,年龄:%d,学号: %d",name,age,number];

NSLog(@"%@",str);

[arr addObject:str];

}

sqlite3_finalize(stmt);

return arr;

}

sqlite3_finalize(stmt);

return [NSMutableArrayarray];

}

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