field
field
description
Syntax
field(Expr e, param1, param2, param3,.....)
在 order by 子句中，可以使用自定义排序，可以将 expr 中的数据按照指定的 param1，2，3 顺序排列。 不在 param 参数中的数据不会参与排序，将会放在最前面，可以使用 asc，desc 控制整体顺序。 如果有 NULL 值，可以使用 nulls first，nulls last 控制 null 的顺序
example
mysql> select k1,k7 from baseall where k1 in (1,2,3) order by field(k1,2,1,3);
+------+------------+
| k1 | k7 |
+------+------------+
| 2 | wangyu14 |
| 1 | wangjing04 |
| 3 | yuanyuan06 |
+------+------------+
mysql> select class_name from class_test order by field(class_name,'Suzi','Ben','Henry');
+------------+
| class_name |
+------------+
| Suzi |
| Suzi |
| Ben |
| Ben |
| Henry |
| Henry |
+------------+
mysql> select class_name from class_test order by field(class_name,'Suzi','Ben','Henry') desc;
+------------+
| class_name |
+------------+
| Henry |
| Henry |
| Ben |
| Ben |
| Suzi |
| Suzi |
+------------+
mysql> select class_name from class_test order by field(class_name,'Suzi','Ben','Henry') nulls first;
+------------+
| class_name |
+------------+
| null |
| Suzi |
| Suzi |
| Ben |
| Ben |
| Henry |
| Henry |
+------------+keywords
field