聚合查询

Chloe 可以像写 sql 一样实现聚合查询。

IQuery q = context.Query();

q.Select(a => Sql.Count()).First();

/*

* SELECT COUNT(1) AS `C` FROM `Users` AS `Users` LIMIT 0,1

*/

/* 支持多个聚合函数 */

q.Select(a => new

{

Count = Sql.Count(),

LongCount = Sql.LongCount(),

Sum = Sql.Sum(a.Age),

Max = Sql.Max(a.Age),

Min = Sql.Min(a.Age),

Average = Sql.Average(a.Age)

}).First();

/*

* SELECT COUNT(1) AS `Count`,COUNT(1) AS `LongCount`,CAST(SUM(`Users`.`Age`) AS SIGNED) AS `Sum`,MAX(`Users`.`Age`) AS `Max`,MIN(`Users`.`Age`) AS `Min`,AVG(`Users`.`Age`) AS `Average`

FROM `Users` AS `Users` LIMIT 0,1

*/

var count = q.Count();

/*

* SELECT COUNT(1) AS `C` FROM `Users` AS `Users`

*/

var longCount = q.LongCount();

/*

* SELECT COUNT(1) AS `C` FROM `Users` AS `Users`

*/

var sum = q.Sum(a => a.Age);

/*

* SELECT CAST(SUM(`Users`.`Age`) AS SIGNED) AS `C` FROM `Users` AS `Users`

*/

var max = q.Max(a => a.Age);

/*

* SELECT MAX(`Users`.`Age`) AS `C` FROM `Users` AS `Users`

*/

var min = q.Min(a => a.Age);

/*

* SELECT MIN(`Users`.`Age`) AS `C` FROM `Users` AS `Users`

*/

var avg = q.Average(a => a.Age);

/*

* SELECT AVG(`Users`.`Age`) AS `C` FROM `Users` AS `Users`

*/