undefined reference to `mysql_init'

[yixuan0719]

I try to make the src code on “CentOS Linux release 7.6.1810 (Core) ” and pop the errors below:
what can i do to resolve these error?

make[2]: 进入目录“/home/juan/openvpn-mysql-auth-0.0.2/tests”
/bin/sh ../libtool --tag=CC --mode=link gcc -g -O2 -g -Wall -Werror -L../src -o testplugin testplugin.o ../src/.libs/libopenvpn-mysql-auth.a
libtool: link: gcc -g -O2 -g -Wall -Werror -o testplugin testplugin.o -L../src ../src/.libs/libopenvpn-mysql-auth.a
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function create_expandable_variable_list': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:109: undefined reference to mysql_real_escape_string'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:113: undefined reference to mysql_real_escape_string' ../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_prepare_mysql':
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:160: undefined reference to mysql_init' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:166: undefined reference to mysql_options'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:170: undefined reference to mysql_real_connect' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:171: undefined reference to mysql_error'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:171: undefined reference to mysql_errno' ../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function _am_mysql_simple_query':
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:207: undefined reference to mysql_query' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:215: undefined reference to mysql_store_result'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:235: undefined reference to mysql_num_rows' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:240: undefined reference to mysql_free_result'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:223: undefined reference to mysql_field_count' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:225: undefined reference to mysql_affected_rows'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:211: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:211: undefined reference to mysql_errno'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:229: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:229: undefined reference to mysql_errno'
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_simple_query': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:268: undefined reference to mysql_close'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:268: undefined reference to mysql_close' ../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function _am_mysql_query_return_row_0':
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:289: undefined reference to mysql_query' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:297: undefined reference to mysql_store_result'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:315: undefined reference to mysql_num_rows' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:328: undefined reference to mysql_num_fields'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:334: undefined reference to mysql_fetch_row' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:341: undefined reference to mysql_fetch_lengths'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:355: undefined reference to mysql_free_result' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:305: undefined reference to mysql_field_count'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:293: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:293: undefined reference to mysql_errno'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:311: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:311: undefined reference to mysql_errno'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:338: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:338: undefined reference to mysql_errno'
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_query_return_row_0': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:383: undefined reference to mysql_close'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:383: undefined reference to mysql_close' ../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function _am_mysql_handle_pf_rules_do_single_query':
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:600: undefined reference to mysql_query' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:608: undefined reference to mysql_store_result'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:626: undefined reference to mysql_num_rows' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:684: undefined reference to mysql_free_result'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:604: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:604: undefined reference to mysql_errno'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:639: undefined reference to mysql_num_fields' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:616: undefined reference to mysql_field_count'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:622: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:622: undefined reference to mysql_errno'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:645: undefined reference to mysql_fetch_row' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:652: undefined reference to mysql_fetch_lengths'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:649: undefined reference to mysql_error' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:649: undefined reference to mysql_errno'
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_handle_auth_user_pass_verify': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:837: undefined reference to mysql_close'
/home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:837: undefined reference to mysql_close' /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:837: undefined reference to mysql_close'
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_library_init': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:846: undefined reference to mysql_server_init'
../src/.libs/libopenvpn-mysql-auth.a(am_mysql.o): In function am_mysql_library_end': /home/juan/openvpn-mysql-auth-0.0.2/src/am_mysql.c:851: undefined reference to mysql_server_end'
collect2: error: ld returned 1 exit status
make[2]: *** [testplugin] 错误 1
make[2]: 离开目录“/home/juan/openvpn-mysql-auth-0.0.2/tests”
make[1]: *** [all-recursive] 错误 1
make[1]: 离开目录“/home/juan/openvpn-mysql-auth-0.0.2”
make: *** [all] 错误 2