mysql 函数

字符函数

大小写转换

mysql> select employee_id,upper(concat(first_name,' ',last_name)) as full_name from employees limit 0,10;
+-------------+------------------+
| employee_id | full_name        |
+-------------+------------------+
|         100 | STEVEN K_ING     |
|         101 | NEENA KOCHHAR    |
|         102 | LEX DE HAAN      |
|         103 | ALEXANDER HUNOLD |
|         104 | BRUCE ERNST      |
|         105 | DAVID AUSTIN     |
|         106 | VALLI PATABALLA  |
|         107 | DIANA LORENTZ    |
|         108 | NANCY GREENBERG  |
|         109 | DANIEL FAVIET    |
+-------------+------------------+
10 rows in set (0.06 sec)

mysql> select employee_id,lower(concat(first_name,' ',last_name)) as full_name from employees limit 0,10;
+-------------+------------------+
| employee_id | full_name        |
+-------------+------------------+
|         100 | steven k_ing     |
|         101 | neena kochhar    |
|         102 | lex de haan      |
|         103 | alexander hunold |
|         104 | bruce ernst      |
|         105 | david austin     |
|         106 | valli pataballa  |
|         107 | diana lorentz    |
|         108 | nancy greenberg  |
|         109 | daniel faviet    |
+-------------+------------------+
10 rows in set (0.06 sec)

mysql> 

concat

···sql
select employee_id,concat(first_name,’ ',last_name) as full_name from employees limit 0,10;
···

mysql> select employee_id,first_name,last_name from employees limit 0,10;
+-------------+------------+-----------+
| employee_id | first_name | last_name |
+-------------+------------+-----------+
|         100 | Steven     | K_ing     |
|         101 | Neena      | Kochhar   |
|         102 | Lex        | De Haan   |
|         103 | Alexander  | Hunold    |
|         104 | Bruce      | Ernst     |
|         105 | David      | Austin    |
|         106 | Valli      | Pataballa |
|         107 | Diana      | Lorentz   |
|         108 | Nancy      | Greenberg |
|         109 | Daniel     | Faviet    |
+-------------+------------+-----------+
10 rows in set (0.07 sec)

mysql> select employee_id,concat(first_name,' ',last_name) as full_name from employees limit 0,10;
+-------------+------------------+
| employee_id | full_name        |
+-------------+------------------+
|         100 | Steven K_ing     |
|         101 | Neena Kochhar    |
|         102 | Lex De Haan      |
|         103 | Alexander Hunold |
|         104 | Bruce Ernst      |
|         105 | David Austin     |
|         106 | Valli Pataballa  |
|         107 | Diana Lorentz    |
|         108 | Nancy Greenberg  |
|         109 | Daniel Faviet    |
+-------------+------------------+
10 rows in set (0.07 sec)

mysql> 

length

mysql> select employee_id,length(concat(first_name,' ',last_name)) as full_name from employees limit 0,10;
+-------------+-----------+
| employee_id | full_name |
+-------------+-----------+
|         100 |        12 |
|         101 |        13 |
|         102 |        11 |
|         103 |        16 |
|         104 |        11 |
|         105 |        12 |
|         106 |        15 |
|         107 |        13 |
|         108 |        15 |
|         109 |        13 |
+-------------+-----------+
10 rows in set (0.06 sec)

mysql> 

substr

mysql> select employee_id,substr(concat(first_name,' ',last_name),1,5) as full_name from employees limit 0,10;
+-------------+-----------+
| employee_id | full_name |
+-------------+-----------+
|         100 | Steve     |
|         101 | Neena     |
|         102 | Lex D     |
|         103 | Alexa     |
|         104 | Bruce     |
|         105 | David     |
|         106 | Valli     |
|         107 | Diana     |
|         108 | Nancy     |
|         109 | Danie     |
+-------------+-----------+
10 rows in set (0.06 sec)

mysql> 

instr

mysql> select employee_id,instr(concat(first_name,' ',last_name),'x') as full_name from employees limit 0,10;
+-------------+-----------+
| employee_id | full_name |
+-------------+-----------+
|         100 |         0 |
|         101 |         0 |
|         102 |         3 |
|         103 |         4 |
|         104 |         0 |
|         105 |         0 |
|         106 |         0 |
|         107 |         0 |
|         108 |         0 |
|         109 |         0 |
+-------------+-----------+
10 rows in set (0.05 sec)

mysql> 

lpad

对 str进行左边填补直至它的长度达到 len个字符长度，然后返回 str。如果 str的长度长于 len’，那么它将被截除到 len个字符。

mysql> select employee_id,lpad(phone_number,20,'*') from employees limit 0,10;
+-------------+---------------------------+
| employee_id | lpad(phone_number,20,'*') |
+-------------+---------------------------+
|         100 | ********515.123.4567      |
|         101 | ********515.123.4568      |
|         102 | ********515.123.4569      |
|         103 | ********590.423.4567      |
|         104 | ********590.423.4568      |
|         105 | ********590.423.4569      |
|         106 | ********590.423.4560      |
|         107 | ********590.423.5567      |
|         108 | ********515.124.4569      |
|         109 | ********515.124.4169      |
+-------------+---------------------------+
10 rows in set (0.06 sec)

mysql>