:original_name: ddm_03_0063.html

.. _ddm_03_0063:

Functions
=========

Supported Functions
-------------------

.. table:: **Table 1** Operator functions

   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | Expression                        | Example                                                                                                                                                                                                                                                                               |
   +===================================+=======================================================================================================================================================================================================================================================================================+
   | IN                                | SELECT \* FROM Products WHERE vendor_id IN ( 'V000001', 'V000010' ) ORDER BY product_price                                                                                                                                                                                            |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | NOT IN                            | SELECT product_id, product_name FROM Products WHERE NOT vendor_id IN ('V000001', 'V000002') ORDER BY product_id                                                                                                                                                                       |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | BETWEEN                           | SELECT id, product_id, product_name, product_price FROM Products WHERE id BETWEEN 000005 AND 000034 ORDER BY id                                                                                                                                                                       |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | NOT...BETWEEN                     | SELECT product_id, product_name FROM Products WHERE NOT vendor_id BETWEEN 'V000002' and 'V000005' ORDER BY product_id                                                                                                                                                                 |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | IS NULL                           | SELECT product_name FROM Products WHERE product_price IS NULL                                                                                                                                                                                                                         |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | IS NOT NULL                       | SELECT id, product_name FROM Products WHERE product_price IS NOT NULL ORDER BY id                                                                                                                                                                                                     |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | AND                               | SELECT \* FROM Products WHERE vendor_id = 'V000001' AND product_price <= 4000 ORDER BY product_price                                                                                                                                                                                  |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | OR                                | SELECT \* FROM Products WHERE vendor_id = 'V000001' OR vendor_id = 'V000009'                                                                                                                                                                                                          |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | NOT                               | SELECT product_id, product_name FROM Products WHERE NOT vendor_id = 'V000002'                                                                                                                                                                                                         |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | LIKE                              | SELECT \* FROM Products WHERE product_name LIKE 'NAME%' ORDER BY product_name                                                                                                                                                                                                         |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | NOT LIKE                          | SELECT \* FROM Products WHERE product_name NOT LIKE 'NAME%' ORDER BY product_name                                                                                                                                                                                                     |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | CONCAT                            | SELECT product_id, product_name, Concat( product_id , '(', product_name ,')' ) AS product_test FROM Products ORDER BY product_id                                                                                                                                                      |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | +                                 | SELECT 3 \* 2+5-100/50                                                                                                                                                                                                                                                                |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | ``-``                             | SELECT 3 \* 2+5-100/50                                                                                                                                                                                                                                                                |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | \*                                | SELECT order_num, product_id, quantity, item_price, quantity*item_price AS expanded_price FROM OrderItems WHERE order_num BETWEEN 000009 AND 000028 ORDER BY order_num                                                                                                                |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | /                                 | SELECT 3 \* 2+5-100/50                                                                                                                                                                                                                                                                |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | UPPER                             | SELECT id, product_id, UPPER(product_name) FROM Products WHERE id > 10 ORDER BY product_id                                                                                                                                                                                            |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | LOWER                             | SELECT id, product_id, LOWER(product_name) FROM Products WHERE id <= 10 ORDER BY product_id                                                                                                                                                                                           |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | SOUNDEX                           | SELECT \* FROM Vendors WHERE SOUNDEX(vendor_name) = SOUNDEX('test') ORDER BY vendor_name                                                                                                                                                                                              |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | IFNULL                            | SELECT IFNULL(product_id, 0) FROM Products;                                                                                                                                                                                                                                           |
   |                                   |                                                                                                                                                                                                                                                                                       |
   |                                   | .. note::                                                                                                                                                                                                                                                                             |
   |                                   |                                                                                                                                                                                                                                                                                       |
   |                                   |    -  For DDM instances created before March 20, sharded tables do not support the calling of functions nested in the IFNULL and aggregation functions. For example, if you execute function **select IFNULL(sum(yan),0) from shenhai**, the result differs from the expected result. |
   |                                   |    -  For DDM instances created after March 20, sharded tables support only the calling of functions nested in the IFNULL and aggregation functions.                                                                                                                                  |
   +-----------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

.. table:: **Table 2** Time and date functions

   +-----------------------+------------------------------------------------------+-----------------------+
   | Expression            | Example                                              | Application Scope     |
   +=======================+======================================================+=======================+
   | DAY()                 | SELECT \* FROM TAB_DATE WHERE DAY(date)=21           | ``-``                 |
   |                       |                                                      |                       |
   |                       | SELECT \* FROM TAB_DATE WHERE date='2018-12-21'      |                       |
   |                       |                                                      |                       |
   |                       | INSERT INTO TAB_DATE(id,date) VALUES(1,'2018-05-22') |                       |
   +-----------------------+------------------------------------------------------+-----------------------+
   | MONTH()               | SELECT \* FROM TAB_DATE WHERE MONTH(date)=12         | ``-``                 |
   |                       |                                                      |                       |
   |                       | SELECT \* FROM TAB_DATE WHERE date='2018-12-21'      |                       |
   |                       |                                                      |                       |
   |                       | INSERT INTO TAB_DATE(id,date) VALUES(1,'2018-05-22') |                       |
   +-----------------------+------------------------------------------------------+-----------------------+
   | YEAR()                | SELECT \* FROM TAB_DATE WHERE YEAR(date)=2018        | ``-``                 |
   |                       |                                                      |                       |
   |                       | SELECT \* FROM TAB_DATE WHERE date='2018-12-21'      |                       |
   |                       |                                                      |                       |
   |                       | INSERT INTO TAB_DATE(id,date) VALUES(1,'2018-05-22') |                       |
   +-----------------------+------------------------------------------------------+-----------------------+

.. table:: **Table 3** Mathematical functions

   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | Expression | Example                                                                                                                     | Application Scope |
   +============+=============================================================================================================================+===================+
   | SQRT()     | SELECT id, product_price, SQRT(product_price) AS price_sqrt FROM Products WHERE product_price < 4000 ORDER BY product_price | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | AVG()      | SELECT AVG(product_price) AS avg_product FROM Products                                                                      | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | COUNT()    | SELECT COUNT(``*``) AS num_product FROM Products                                                                            | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | MAX()      | SELECT id, product_id, product_name, MAX(product_price) AS max_price FROM Products ORDER BY id                              | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | MIN()      | SELECT id, product_id, product_name, MIN(product_price) AS min_price FROM Products ORDER BY id                              | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+
   | SUM()      | SELECT SUM(product_price) AS sum_product FROM Products                                                                      | ``-``             |
   +------------+-----------------------------------------------------------------------------------------------------------------------------+-------------------+

Unsupported Functions
---------------------

.. table:: **Table 4** Function restrictions

   =========== ==========================================
   Item        Restriction
   =========== ==========================================
   ROW_COUNT() Function **ROW_COUNT()** is not supported.
   =========== ==========================================