LightDB - 支持 curdate, current_date 函数[mysql兼容]

从23.4 版本开始， LightDB 支持mysql 的curdate, current_date 函数。

curdate, current_date

current_date 与 curdate相同， 都是用来获取当前时间，下面是mysql 中的介绍：

Returns the current date as a value in ‘YYYY-MM-DD’ or YYYYMMDD format, depending on whether the function is used in string or numeric context.

注意点

在LightDB 中使用这两个函数有几个需要注意的点：

• 返回值类型为date类型， 只能返回’YYYY-MM-DD’ 格式， 不能返回 YYYYMMDD format， 加法减法与mysql效果不同
• curdate() 不能参与乘法或除法

示例

lightdb:

lightdb@test_m=# select curdate();
  curdate   
------------
 2023-12-06
(1 row)

lightdb@test_m=# select current_date();
 current_date 
--------------
 2023-12-06
(1 row)

lightdb@test_m=# select curdate()+1;
  ?column?  
------------
 2023-12-07
(1 row)

lightdb@test_m=# select curdate()/2;
ERROR:  operator does not exist: date / integer
LINE 1: select curdate()/2;
                        ^
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
lightdb@test_m=# select curdate()*2;
ERROR:  operator does not exist: date * integer
LINE 1: select curdate()*2;
                        ^
HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
lightdb@test_m=# select curdate()-2;
  ?column?  
------------
 2023-12-04
(1 row)

mysql:

mysql> select curdate();
+------------+
| curdate()  |
+------------+
| 2023-12-06 |
+------------+
1 row in set (0.00 sec)

mysql> select current_date();
+----------------+
| current_date() |
+----------------+
| 2023-12-06     |
+----------------+
1 row in set (0.00 sec)

mysql> select curdate()+1;
+-------------+
| curdate()+1 |
+-------------+
|    20231207 |
+-------------+
1 row in set (0.00 sec)

mysql> select curdate()/2;
+---------------+
| curdate()/2   |
+---------------+
| 10115603.0000 |
+---------------+
1 row in set (0.00 sec)

mysql> select curdate()*2;
+-------------+
| curdate()*2 |
+-------------+
|    40462412 |
+-------------+
1 row in set (0.00 sec)

mysql> select curdate()-1;
+-------------+
| curdate()-1 |
+-------------+
|    20231205 |
+-------------+
1 row in set (0.00 sec)

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