Add support for recent versions of MySQL.jl

Greetings!

I tried using BioMedQuery.jl for the first time today. Installation went smoothly, however, when I attempt to load the package, I run into an error during the pre-compilation step:

julia> using BioMedQuery
[ Info: Precompiling BioMedQuery [e96904bf-1073-5077-9b57-b0ce0ff5555a]
ERROR: LoadError: LoadError: LoadError: UndefVarError: MySQLHandle not defined
Stacktrace:
 [1] top-level scope at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/DBUtils/mysql_db_utils.jl:55
 [2] include(::String) at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/BioMedQuery.jl:4
 [3] top-level scope at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/DBUtils/DBUtils.jl:4
 [4] include(::String) at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/BioMedQuery.jl:4
 [5] top-level scope at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/BioMedQuery.jl:21
 [6] top-level scope at none:2
 [7] eval at ./boot.jl:331 [inlined]
in expression starting at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/DBUtils/mysql_db_utils.jl:55
in expression starting at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/DBUtils/DBUtils.jl:4
in expression starting at /home/keith/.julia/packages/BioMedQuery/Ps32f/src/BioMedQuery.jl:21
ERROR: Failed to precompile BioMedQuery [e96904bf-1073-5077-9b57-b0ce0ff5555a] to /home/keith/.julia/compiled/v1.4/BioMedQuery/I7mWp_L3y04.ji.

Looking at the code for src/DBUtils/mysql_db_utils.jl, I noticed that the function db_query() is attempting to call MySQL.query(), which doesn't appear to be in the current API for MySQL.jl.

I'm guessing that the MySQL.jl API has changed in some recent version, and that BioMedQuery.jl is still referring to the old interface? It's also possible that I am just misunderstanding something..

As a side note, I also noticed that init_mysql_database() function that gets automatically called during the initial attempt to load BioMedQuery.jl attempts to look for the "test" database. Since it is common to remove the test db after installation, it might be good to avoid this, if possible.

Thanks!

System Info

• Arch Linux 5.6.14 (64-bit)
• Julia 1.4.2
• MariaDB 10.4.13

Package versions:

• [39abe10b] MySQL v1.0.4
• [e96904bf] BioMedQuery v0.6.6 #master (https://github.com/JuliaHealth/BioMedQuery.jl.git)

Start with src/DBUtils/mysql_db_utils.jl, especially db_query(), and compare its MySQL.query()/MySQLHandle usage with the current MySQL.jl API. Also inspect init_mysql_database() and the loading path in src/DBUtils/DBUtils.jl and src/BioMedQuery.jl. Done means BioMedQuery precompiles with recent MySQL.jl versions and does not require the test database to load.