Question

我有一个带有列的SQLite表，如下所述，

Table1
ID, Topics,    Rating, Comments
1   topic1      3      none
2   topic1      4      none
3   topic2      2      none
4   topic2      4      none

我想使用sqlite查询为所有topic1，topic2添加评级列。如何形成这个sqlite查询？

感谢。

Answer 1

您可以使用SUM() aggregate function来实现此目标。

你可以这样做：

SELECT SUM(Rating) from Table1 WHERE Topics="topic1";

Answer 2

NSString *getQuery = [NSString stringWithFormat:@"SELECT SUM(Rating) from Table1 WHERE Topics='topic1'"];

然后将其传递给下面的方法

-(NSMutableArray*) getRecords :(NSString*)getQuery isCheckOperationId:(BOOL)checkOperation
{
const char *dbpath = [databasePath UTF8String];    
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
    const char *query_stmt = [getQuery UTF8String];

    sqlite3_prepare_v2(database, query_stmt, -1, &statement, NULL);
    NSMutableArray *jsonArray = [NSMutableArray new];
    while (sqlite3_step(statement) == SQLITE_ROW)
    {
        NSMutableArray *objectColumn = [NSMutableArray new];
        NSMutableArray *keysColumn = [NSMutableArray new];
        for (int i=0; i < sqlite3_column_count(statement); i++) 
        {
            [objectColumn addObject:[NSString stringWithUTF8String:(const char *) sqlite3_column_text(statement, i)]];
            [keysColumn addObject:[NSString stringWithUTF8String:(const char *) sqlite3_column_name(statement, i)]];
        }

        NSArray *objects=[[NSArray alloc]initWithArray:objectColumn];
        NSArray *keys=[[NSArray alloc]initWithArray:keysColumn];
        NSDictionary *dict=[NSDictionary dictionaryWithObjects:objects forKeys:keys];
        [jsonArray addObject:dict];
       }

    [self closeDatabase];
    return jsonArray;
}

return nil;

}

希望这可以帮助你!!!

在SQLite中使用RatingColumn

2 个答案: