Question

我创建了一个包含三个条目名称，地址和电话号码的表格。现在我想根据名称文本字段中输入的名称删除数据。我成功地做了这个，但问题是如果我输入一个不在我的数据库标签中的名称仍然显示'联系人已删除'...这是我的代码

   -(void)deleteContact{
      const char *dbPath=[databasePath UTF8String];
      sqlite3_stmt *statement;
      if (sqlite3_open(dbPath, &contactDB)==SQLITE_OK)
          {

    NSString *querySQL=[NSString stringWithFormat:@"delete from 
                contacts where name=\"%@\"",name.text];
    const char *query_stmt=[querySQL UTF8String];
        sqlite3_prepare_v2(contactDB, query_stmt,-1,&statement, NULL);
        (sqlite3_step(statement)==SQLITE_OK); 

            status.text=@"Contact Deleted"; 
    name.text=@"";
    address.text=@"";
    phone.text=@"";

        sqlite3_finalize(statement);

    }
sqlite3_close(contactDB);

[name resignFirstResponder];
}

Answer 1

从YourTable中删除name =“NameToDelete”
将从表YourTable中删除字段名称等于NameToDelete的所有记录。

Answer 2

即使没有要删除的内容，删除也没问题。如果您需要知道是否有任何要删除的内容，请查看此内容。

NSString *sql = [NSString stringWithFormat:@"select count (*) from contacts where name=\"%@\"", name.text];
sqlite3_stmt *stmt;
int res = sqlite3_prepare_v2(database, [sql UTF8String], -1, &stmt, NULL);
if (res != SQLITE_OK) {
    NSLog(@"sqlite3_prepare_v2() failed");
    return;
}
int count = 0;
if (sqlite3_step(stmt) == SQLITE_ROW) {
    count = sqlite3_column_int(stmt, 0);
}
sqlite3_finalize(stmt);

if (count == 0) {
    // nothing to delete, do whatever you like
} else {
    // do real delete
    // your code for that seems to be OK
}

如何从sqlite中删除数据

2 个答案: