ios sqlite3 curd 小笔记

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定义个sqlite3

sqlite3 *_db;

一些方法的说明：

sqlite3 *db 数据库句柄

sqlite3_stmt *stmt

sqlite3_open() 打开数据库(没有数据库就创建)

sqlite3_exec() 执行非查询的sql语句

sqlite3_step() 调用sqlite3_prepare方法后sqlite3_step()函数将在记录集中移动

sqlite3_finalize() 释放结果集

sqlite3_close() 关闭数据库

1.创建/打开数据库

-(void)open_sqlite{    NSString *filename = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"test.sqlite"];     int result = sqlite3_open(filename.UTF8String, &_db);    if (result == SQLITE_OK) {                //create table t_product                /**            sqlite3_exec(sqlite3*,const char *sql,int (*callback)(void*,int,char**,char**),void *,char **errmsg)          **/                //sql 语句        const char *sql = "create table if not exists t_product(p_id integer primary key autoincrement,p_name text,p_number integer);";        char *errorMsg = NULL;        int result = sqlite3_exec(_db,sql,NULL,NULL,&errorMsg);        if(result == SQLITE_OK){            NSLog(@"create table OK !");        }else{            NSLog(@"create table error：%s",errorMsg);        }            }else{        NSLog(@"open database error!");    }}

2. 查询数据

- (IBAction)query:(UIButton *)sender {        //执行一条p_id名称包含'3'语句    const char *sql = "select p_id, p_name ,p_number from t_product where p_id like ?";        //定义stmt结果集    sqlite3_stmt *stmt = NULL;    /**        sqlite3_prepare_v2(sqlite3 *db,const char *zSql,int nByte,sqlite3_stmt **ppStmt,const char **pzTail)     **/    int result = sqlite3_prepare_v2(_db,sql,-1,&stmt,NULL);        if (result == SQLITE_OK) {        NSLog(@"prepare OK");                NSString *condition = [NSString stringWithFormat:@"%%%@%%",@"1"];        // 设置占位符的内容        sqlite3_bind_text(stmt,1,condition.UTF8String,-1,NULL);                //执行SQL语句，从结果集中取出数据        // int stepResult = sqlite3_step(stmt);        while (sqlite3_step(stmt) == SQLITE_ROW) {                        int pid = sqlite3_column_int(stmt,0);            const unsigned char *pname = sqlite3_column_text(stmt,1);            int pnumber = sqlite3_column_int(stmt,2);            NSLog(@"%d %s %d", pid, pname, pnumber);        }    }else{        NSLog(@"prepare error");    }}

3.更新数据库

- (IBAction)update:(UIButton *)sender {    const char *sql = "insert or replace into t_product (p_id,p_name,p_number) values(10,'product_new',20)";    char *errorMsg = NULL;    int result = sqlite3_exec(_db, sql, NULL, NULL, &errorMsg);    if (result == SQLITE_OK) {        NSLog(@"update data success !");    }else{        NSLog(@"update data error :%s",errorMsg);    }}

4.删除某一条数据

- (IBAction)delete:(UIButton *)sender {        const char *sql = "delete from t_product where p_id = 10 ";    char *errorMsg = NULL;    int result = sqlite3_exec(_db, sql, NULL, NULL, &errorMsg);    if (result == SQLITE_OK) {        NSLog(@"delete data success !");    }else{        NSLog(@"delete data error :%s",errorMsg);    }}

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