李洪强iOS开发之-sql数据库的使用

一,创建工程

二: 导入头文件

三:导入

四: 数据库增删改查

//因为是结构体类型,所以用assign

//1.创建数据库(保存路径)

@property(nonatomic,assign)sqlite3 *db;

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

//结构体类型的指针

//    sqlite3 *db = NULL;

//打开数据库,如果没有就创建

NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject] stringByAppendingPathComponent:@"dasta.sqlite"];

NSLog(@"%@",path);

int success = sqlite3_open(path.UTF8String, &_db);

if(success == SQLITE_OK){

NSLog(@"创建数据库成功!");

//2.创建表(指定字段,需求,保存学生信息 id name score)

//用sql语句

NSString *str = @"CREATE TABLE IF NOT EXISTS t_student (id INTEGER PRIMARY KEY AUTOINCREMENT ,name TEXT NOT NULL,score REAL NOT NULL)";

//执行

int success_t =  sqlite3_exec(_db, str.UTF8String, NULL, NULL, NULL);

if(success_t == SQLITE_OK){

NSLog(@"创建表成功!");

}else{

NSLog(@"创建表失败!");

}

}else{

NSLog(@"创建数据库失败!");

}

//关闭数据库,至于在什么时候关闭,取决于自己的需求

sqlite3_close(_db);

}

//3.增加 (100条数据  数据随机)

- (IBAction)insertData:(UIButton *)sender {

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

NSString *strName = [NSString stringWithFormat:@"ming-yuexing-%d",i];

NSString *sqlStr = [NSString stringWithFormat:@"INSERT INTO t_student (name , score) VALUES ('%@',%.2f)",strName,arc4random_uniform(1000)/10.0];

//执行

int success = sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if(success == SQLITE_OK){

NSLog(@"添加成功");

}else{

NSLog(@"添加失败");

}

}

}

//4.删除 (70-80分数)

- (IBAction)deleteData:(UIButton *)sender {

NSString *sqlStr = @"DELETE FROM t_student WHERE score > 70.0 AND score < 80.0";

//执行

int success = sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if(success == SQLITE_OK){

NSLog(@"删除成功");

}else{

NSLog(@"删除失败");

}

}

//5.修改 (修改小于60.0的 为60.0)

- (IBAction)updateData:(UIButton *)sender {

NSString *sqlStr = @"UPDATE t_student SET score = 60.0 WHERE score < 60.0";

//执行

int success = sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if(success == SQLITE_OK){

NSLog(@"修改成功");

}else{

NSLog(@"修改失败");

}

}

//6.查询

- (IBAction)selectData:(UIButton *)sender {

//    (查成绩  >= 60)

//    NSString *sqlStr = @"SELECT * FROM t_student WHERE score > 60.0 ORDER BY score DESC";

//查询数据 (name中带 8 的)

//8% 意思是以8开头

//%8 意思是以8结尾

NSString *sqlStr = @"SELECT * FROM t_student WHERE name LIKE '%8'";

//查询之后,把结果放在stmt对象

//保存所有的结果集

sqlite3_stmt *stmt = nil;

sqlite3_prepare(_db, sqlStr.UTF8String, -1, &stmt, NULL);

//获取到所有的结果 每一步 查询到一条记录

sqlite3_step(stmt);

while (sqlite3_step(stmt) == SQLITE_ROW) {

//取出一条记录

//name TEXT score REAL

//从第几列告诉我

const unsigned char * name = sqlite3_column_text(stmt, 1);

NSString *strName = [NSString stringWithCString:(const char *)name encoding:NSUTF8StringEncoding];

//score

double score = sqlite3_column_double(stmt, 2);

NSLog(@"name = %@ score = %f",strName,score);

}

}

@end