sqlite3基本操作

　　在移动设备上进行高性能高效率的大量数据存储，我们一般用得时sqlite这款轻巧型的数据库，这里介绍其增删改查基本功能

　　在ios开发中我们需要先导入"libsqlite3.dylib"这个动态库，然后在控制器中#import "sqlite3.h"

　　在类扩展中定义成员变量：sqlite3 *_db

　　然后定义数据库文件在手机沙盒中的存储位置以及数据库名称：

NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

NSString *fileName = [path stringByAppendingPathComponent:@"myData.sqlite"];

　　执行打开数据库操作：sqlite3_open([fileName UTF8String], &_db) 

　　如果数据库是正常打开，我们可以根据需要来创建数据表：

CREATE TABLE IF NOT EXISTS cPerson(id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT,age INTEGER)

　　然后可以对数据表的数据进行增删改查等操作：

　　增：INSERT INTO cPerson (id, name, age) VALUES ('2','hehe','20')"

　　删：DELETE FROM cPerson WHERE id = 2

　　改：UPDATE cPerson set name = 'ashui' where id = 2

　　查：SELECT * FROM cPerson

　　最后执行关闭数据库操作：sqlite3_close(_db)

　　绑定VALUES(?,?)中?的值：sqlite3_bind_text(sqlite3_stmt *, int, const char *,int n, void (*)(void *))

　　具体代码实现：

#import "WYSViewController.h"
#import "sqlite3.h"

@interface WYSViewController (){
    
    // 数据库
    sqlite3 *_db;
}

@end

@implementation WYSViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString *fileName = [path stringByAppendingPathComponent:@"myData.sqlite"];
    
    // 打开数据库
    if (sqlite3_open([fileName UTF8String], &_db) == SQLITE_OK){
        
        NSLog(@"数据库打开成功");
        
        // 如果不存在，则创建表
        NSString *cPerson = [NSString stringWithFormat:@"CREATE TABLE IF NOT EXISTS cPerson(id integer primary key autoincrement,name text,age integer)"];
        [self executeWithString:cPerson];
        
    }
}

// 执行操作
- (void)executeWithString:(NSString *)string
{
    char *error = nil;
    
    if (sqlite3_exec(_db, [string UTF8String], NULL, NULL, &error) == SQLITE_OK){
        
        NSLog(@"操作成功");
    }

}

- (IBAction)insertData:(id)sender{
    
    NSString *iP1 = [NSString stringWithFormat:@"INSERT INTO cPerson (id, name, age) VALUES ('%d','%@','%d')",2,@"hehe",20];
    [self executeWithString:iP1];
    
    NSString *iP2 = [NSString stringWithFormat:@"INSERT INTO cPerson (id, name, age) VALUES ('%d','%@','%d')",3,@"haha",22];
    [self executeWithString:iP2];
}

// 删除数据
- (IBAction)deleteData:(id)sender {
    
    NSString *dPerson = [NSString stringWithFormat:@"DELETE FROM cPerson WHERE id = 2"];
    
    [self executeWithString:dPerson];
    
    // 这种删除方式也行
    //    sqlite3_stmt *statement; // 用于保存编译好的SQL语句
    //
    //    if (sqlite3_prepare_v2(_db, [dPerson UTF8String], -1, &statement, nil) == SQLITE_OK){
    //
    //        while (sqlite3_step(statement) == SQLITE_ROW) {
    //
    ////            if (sqlite3_step(statement) == SQLITE_DONE){
    //    
    ////            }
    //        }
    //
    //        NSLog(@"删除成功");
    //
    //        sqlite3_finalize(statement);
    //    }
    
    //    sqlite3_close(_db);
}

// 更新数据
- (IBAction)updataData:(id)sender {
    
    NSString *uPerson = [NSString stringWithFormat:@"UPDATE cPerson set name = 'shuige' where id = 3"];
    
    [self executeWithString:uPerson];
    
    
}

// 查询数据
- (IBAction)selectData:(id)sender {
    
    
    NSString *sPerson = @"SELECT * FROM cPerson";
    sqlite3_stmt *statement;
    
    if (sqlite3_prepare_v2(_db, [sPerson UTF8String], -1, &statement, nil) == SQLITE_OK){
        
        while(sqlite3_step(statement) == SQLITE_ROW){
            
            int id = sqlite3_column_int(statement, 0);
            
            char *name = (char *)sqlite3_column_text(statement, 1);
            
            NSString *nameStr = [[NSString alloc] initWithUTF8String:name];
            
            int age = sqlite3_column_int(statement, 2);
            
            NSLog(@"id:%d  name:%@   age:%d",id,nameStr,age);
        }
        
        sqlite3_finalize(statement);
    }
    
}
@end