Purpose
This function converts all English letters in a string to uppercase.
Syntax
UPPER(char)
Parameters
char is the string to be converted. The data type can be CHAR, VARCHAR2, NCHAR, NVARCHAR2, or CLOB.
Return type
The same data type as char.
Examples
Convert the string OceanBase to uppercase.
obclient> SELECT UPPER('OceanBase') "UPPER" FROM DUAL;
+-----------+
| UPPER |
+-----------+
| OCEANBASE |
+-----------+
1 row in set