keep_user_target_list_in_result 保持查询结果集列名与用户指定大小写一致

在 MatrixOne 查询中，保持结果集列名与用户指定的名称大小一致，除了可以通过使用别名（alias）来实现，还可以通过设置参数来实现。

keep_user_target_list_in_result 是 MatrixOne 设置查询结果集列名与用户指定的名称大小写是否一致的一个全局参数。

查看 keep_user_target_list_in_result

在 MatrixOne 中使用以下命令查看 keep_user_target_list_in_result：

--默认为 1
show variables like "keep_user_target_list_in_result";
select @@keep_user_target_list_in_result;

设置 keep_user_target_list_in_result

在 MatrixOne 中使用以下命令设置 keep_user_target_list_in_result：

--默认为 1，重新连接数据库生效
set global keep_user_target_list_in_result = 0;

示例

create table t1(aa int, bb int, cc int, AbC varchar(25), A_BC_d double);
insert into t1 values (1,2,3,'A',10.9);

mysql> select * from t1; 
+------+------+------+------+--------+
| aa   | bb   | cc   | abc  | a_bc_d |
+------+------+------+------+--------+
|    1 |    2 |    3 | A    |   10.9 |
+------+------+------+------+--------+
1 row in set (0.00 sec)

mysql> select @@keep_user_target_list_in_result; --查询参数值，默认开启
+-----------------------------------+
| @@keep_user_target_list_in_result |
+-----------------------------------+
| 1                                 |
+-----------------------------------+
1 row in set (0.01 sec)

mysql> select aA, bB, CC, abc, a_Bc_D from t1;--在开启情况下，查询结果集列名与用户指定的名称大小写一致
+------+------+------+------+--------+
| aA   | bB   | CC   | abc  | a_Bc_D |
+------+------+------+------+--------+
|    1 |    2 |    3 | A    |   10.9 |
+------+------+------+------+--------+
1 row in set (0.00 sec)

mysql> set global keep_user_target_list_in_result =0;--关闭查询结果集列名与用户指定的名称大小一致设置
Query OK, 0 rows affected (0.01 sec)

mysql> exit;--退出数据库重新连接后参数生效

mysql> show variables like "keep_user_target_list_in_result";
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| keep_user_target_list_in_result | 0     |
+---------------------------------+-------+
1 row in set (0.00 sec)

mysql> select aA, bB, CC, abc, a_Bc_D from t1;--在设置关闭情况下，查询结果集列名与用户指定的名称大小写不一致
+------+------+------+------+--------+
| aa   | bb   | cc   | abc  | a_bc_d |
+------+------+------+------+--------+
|    1 |    2 |    3 | A    |   10.9 |
+------+------+------+------+--------+
1 row in set (0.00 sec)