ws_substring - MySQL UDF for substring.

about

This is MySQL User Defined Function written by cgo.
Substring function.

arg	explain
arg1	input input string
arg2	start start position (0 is first)
arg3	length substring length

why substring?

MySQL has already substring function.
But, when I tried to substring a huge text via JDBC or ADO.NET,
Incorrect string value: error was happened.
I don't understarnd why this error is happened, so I try to create this udf.

how to install

$ ./build.sh

(notice)

• require root privilege

example

(simple1)

MariaDB [(none)]> select ws_substring('aaabbbccc', 3, 3);
+---------------------------------+
| ws_substring('aaabbbccc', 3, 3) |
+---------------------------------+
| bbb                             |
+---------------------------------+

(simple2)

MariaDB [(none)]> select ws_substring('𠮷野家で𠮷野がご飯をたべる', 3, 3);
+-----------------------------------------------------------+
| ws_substring('?野家で?野がご飯をたべる', 3, 3)            |
+-----------------------------------------------------------+
| で𠮷野                                                    |
+-----------------------------------------------------------+