feat: support function aliases and add MySQL-compatible aliases (#7410)

* feat: support function aliases and add MySQL-compatible aliases

Signed-off-by: Dennis Zhuang <killme2008@gmail.com>

* fix: get_table_function_source

Signed-off-by: Dennis Zhuang <killme2008@gmail.com>

* refactor: add function_alias mod

Signed-off-by: Dennis Zhuang <killme2008@gmail.com>

* fix: license

Signed-off-by: Dennis Zhuang <killme2008@gmail.com>

---------

Signed-off-by: Dennis Zhuang <killme2008@gmail.com>

tests/cases/standalone/common/function/function_alias.result

@@ -0,0 +1,72 @@
+-- MySQL-compatible function alias tests
+-- ucase -> upper
+SELECT
+    ucase('dataFusion') AS ucase_value,
+    upper('dataFusion') AS upper_value;
+
++-------------+-------------+
+| ucase_value | upper_value |
++-------------+-------------+
+| DATAFUSION  | DATAFUSION  |
++-------------+-------------+
+
+-- lcase -> lower
+SELECT
+    lcase('DataFusion') AS lcase_value,
+    lower('DataFusion') AS lower_value;
+
++-------------+-------------+
+| lcase_value | lower_value |
++-------------+-------------+
+| datafusion  | datafusion  |
++-------------+-------------+
+
+-- ceiling -> ceil
+SELECT
+    ceiling(1.2) AS ceiling_pos,
+    ceil(1.2) AS ceil_pos,
+    ceiling(-1.2) AS ceiling_neg,
+    ceil(-1.2) AS ceil_neg;
+
++-------------+----------+-------------+----------+
+| ceiling_pos | ceil_pos | ceiling_neg | ceil_neg |
++-------------+----------+-------------+----------+
+| 2.0         | 2.0      | -1.0        | -1.0     |
++-------------+----------+-------------+----------+
+
+-- mid -> substr
+SELECT
+    mid('datafusion', 5, 3) AS mid_value,
+    substr('datafusion', 5, 3) AS substr_value;
+
++-----------+--------------+
+| mid_value | substr_value |
++-----------+--------------+
+| fus       | fus          |
++-----------+--------------+
+
+-- rand -> random
+-- NOTE: RAND([seed]) is supported by MySQL, but seed is not supported here.
+-- This test only validates that rand() exists and returns values in [0, 1).
+SELECT rand() >= 0.0 AND rand() < 1.0 AS rand_in_range;
+
++---------------+
+| rand_in_range |
++---------------+
+| true          |
++---------------+
+
+-- std -> stddev_pop, variance -> var_pop
+SELECT
+    round(std(x), 6) AS std_value,
+    round(stddev_pop(x), 6) AS stddev_pop_value,
+    round(variance(x), 6) AS variance_value,
+    round(var_pop(x), 6) AS var_pop_value
+FROM (VALUES (1.0), (2.0), (3.0)) AS t(x);
+
++-----------+------------------+----------------+---------------+
+| std_value | stddev_pop_value | variance_value | var_pop_value |
++-----------+------------------+----------------+---------------+
+| 0.816497  | 0.816497         | 0.666667       | 0.666667      |
++-----------+------------------+----------------+---------------+
+

tests/cases/standalone/common/function/function_alias.sql

@@ -0,0 +1,36 @@
+-- MySQL-compatible function alias tests
+
+-- ucase -> upper
+SELECT
+    ucase('dataFusion') AS ucase_value,
+    upper('dataFusion') AS upper_value;
+
+-- lcase -> lower
+SELECT
+    lcase('DataFusion') AS lcase_value,
+    lower('DataFusion') AS lower_value;
+
+-- ceiling -> ceil
+SELECT
+    ceiling(1.2) AS ceiling_pos,
+    ceil(1.2) AS ceil_pos,
+    ceiling(-1.2) AS ceiling_neg,
+    ceil(-1.2) AS ceil_neg;
+
+-- mid -> substr
+SELECT
+    mid('datafusion', 5, 3) AS mid_value,
+    substr('datafusion', 5, 3) AS substr_value;
+
+-- rand -> random
+-- NOTE: RAND([seed]) is supported by MySQL, but seed is not supported here.
+-- This test only validates that rand() exists and returns values in [0, 1).
+SELECT rand() >= 0.0 AND rand() < 1.0 AS rand_in_range;
+
+-- std -> stddev_pop, variance -> var_pop
+SELECT
+    round(std(x), 6) AS std_value,
+    round(stddev_pop(x), 6) AS stddev_pop_value,
+    round(variance(x), 6) AS variance_value,
+    round(var_pop(x), 6) AS var_pop_value
+FROM (VALUES (1.0), (2.0), (3.0)) AS t(x);