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How to setup multiple datasources with different versions of the same jdbc driver?

I have to deploy to tomcat7 server, an application that connect to two databases:
Oracle Database 12.1.0.2 which need the ojdbc7.jar
Oracle Database 11.2.0.4 which uses ojdbc6.jar
I created two datasources that uses the same class from both libs, now I need to copy libs into $CATALINA_HOME/lib, I fear ending up with calssloader conflit as the two jars share many classes with same className.
type="javax.sql.DataSource"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
driverClassName="oracle.jdbc.OracleDriver"
How to deal with that ?

SQL Azure and Connection Pooling

I have been searching high and low and gathered bits and pieces, apologies if this has already been answered elsewhere but I am unable to find it.
I am writing a web application in Java with Tomcat, and SQL Azure in the backend.
There are multiple servlets accessing the SQL Azure DB. I would like to use Connection Pools as managed by Tomcat 8.5
My application context.xml in META-INF is as follows:
<Context>
<Resource name="jdbc/sqlazure"
auth="Container"
driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
type="javax.sql.DataSource"
maxIdle="30"
username="[username]"
password="[password]"
url="jdbc:sqlserver://[database]:1433;database=BackInfo;encrypt=true;trustServerCertificate=false;hostNameInCertificate=*.database.windows.net;loginTimeout=30"
removeAbandonedTimeout="30"
logAbandoned="true" />
</Context>
In the Java Code, I access the typical way:
InitialContext ic = new InitialContext();ds = (DataSource)ic.lookup("java:comp/env/jdbc/sqlazure");
try(Connection con = ds.getConnection())....
Everything seems to work, so let me confirm my understanding here:
I do not need to specify a separate web.xml since I'm using Tomcat 8.5. Correct ?
Azure will automatically create a pool when I connect in this manner. The number of connections in the pool etc cannot (do not need to?) be configured.
Before I realized I would have other servlets that need to access the database, I had one servlet directly creating a Datasource via SQLServerConnectionPoolDataSource and getting a connection from there. The documentation states:
SQLServerConnectionPoolDataSource is typically used in Java Application Server environments that support built-in connection pooling and require a ConnectionPoolDataSource to provide physical connections, such as Java Platform, Enterprise Edition (Java EE) application servers that provide JDBC 3.0 API spec connection pooling.
Does this mean that when I use SQLServerConnectionPoolDataSource directly to ask for a connection, it will check if Tomcat supports pooling and then is basically using JDBC mechanisms to create a pool of SQL Azure connections managed by Tomcat ?
When getting the DataSource via Tomcat JNDI lookup, using SQLServerDriver as specified in context.xml. When the web app starts up, it will check context.xml and use SQLServerDriver to connect to SQL Azure, check if pooling is supported, if yes then Tomcat is using the driver to automatically creating a connection pool DataSource that it returns ?
I also just thought of one other question. Would it make sense to have a Singleton DataSource class that returns a reference to the pooled connection DataSource, or would it be better to have each servlet lookup the datasource in its init() and store in a private variable ?
Thanks

Based on my understanding, the jdbc connection pool for SQL Server is created by Java Application, not Azure does. My suggestion is that you need to refer to the Tomcat offical documents below to understand the JNDI Resources & JDBC DataSource.
JNDI Resources: http://tomcat.apache.org/tomcat-8.5-doc/jndi-resources-howto.html
JDBC DataSource: http://tomcat.apache.org/tomcat-8.5-doc/jndi-datasource-examples-howto.html

Remote MySQL DB and eclipse

I am currently trying to implement a simple servlet that has to communicate with our database.
I have no real prior experience with databases, so I was wondering how I should I go about this? I have downloaded the mysql-connector-java-5.1.40 from dev.mysql.
Going over some of the directions on the web for setting up the connection, it seems to only be for local mysql, but what of remote? The remote's user and pass is demo/demo; of course I would also need to log into the the remote server with my credentials. How do I go about connecting to this remote db?
Edit: So I believe I successfully connected to the DB, at least I can see it in my eclipse under data sources and the tables are present (company and stock_prices), however my eclipse still says I have an unsuitable driver even though I do have one associated with it.

The proper way of consuming a database resources in a web container (or in an application server) is through the javax.sql.DataSource abstraction. So you should configure a data source in your container. For tomcat it's as simple as creating a file named context.xml in your war's META-INF folder with the following content (replace address and credentials with your own):
<Context>
<Resource name="jdbc/[YourDatabaseName]"
auth="Container"
type="javax.sql.DataSource"
username="[DatabaseUsername]"
password="[DatabasePassword]"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql:/[yourserver]:3306/[your-db]"
maxActive="20"
maxIdle="20"/>
</Context>
Then when you want to perform a DB operation:
you either look up the data source:
DataSource ds =(DataSource) new InitialContext().lookup("java:comp/env/jdbc[YourDatabaseName]");
or simply use dependency injection for managed components like servlets:
#Resource(name="jdbc/YourDataSource")
Datasource ds;
The you just get a connection from the datasource in order to execute statements to the database.
The DB driver can be put in one of two places:
the war's lib folder
tomcat's lib folder
It's recommended to put it in tomcat's lib, because drivers are singletons and if you have several apps with different versions of the driver in the same container bad things will happen.
How do I go about connecting to this remote db?
Connecting to a remote DB is the same as connecting to alocal DB. Just pass the correct DB address in the connection string.

Where are my tables in H2?

I deploy my web app to the WildFly 8.02 Final server. I use default out of the box DataSource that comes with the server with jndi name space:
java:jboss/datasources/ExampleDS
and I use default url:
jdbc:h2:mem:test;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
to access H2 from IntelliJ IDEA database client tool or other client applications (I use url connection, because tcp connection via default port doesn't work).
The app is basically an empty WAR with just entity beans and persistence.xml file. I intend to test purely what tables will be created in the underlying data source in accordance to my annotations.
Here is the thing: when I set in persistence.xml:
<property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
war is succesfully deployed, but when I connect via any client tool to the H2 data source I can see only pre-defined tables after:
SELECT * FROM INFORMATION_SCHEMA.TABLES
I can create tables via client tools and I am able to track their existence by the previous SQL query. So it seems that tables just hadn't been created by the JPA framework.
But when I change persistence.xml to the different schema creation mode:
<property name="javax.persistence.schema-generation.database.action" value="create"/>
Deployment will fail with jdbc exception telling that JPA tries to create already existing tables, but at the same time client tools still do not show any user created tables.
Thx.

Take a look at http://www.h2database.com/html/features.html#in_memory_databases :
To access an in-memory database from another process or from another computer,
you need to start a TCP server in the same process as the in-memory database
was created. The other processes then need to access the database over TCP/IP
or TLS, using a database URL such as: jdbc:h2:tcp://localhost/mem:db1.
Look here for an example:
H2 database in memory mode cannot be accessed by Console

How to configure tomcat 6.0 for mysql

I'm using Tomcat 6.0, and I want to know how can I configure Tomcat's server.xml file to connect to mysql database, and enable form based authentication in java.
I'm currently using mysql 5.1, and I've already downloaded mysql connector jar file, and put in lib directory of Tomcat.

I'm guessing you want Tomcat to create connection pool to MySQL database. In that case, you don't need to configure server.xml file. In the context.xml file you need to add a <Resource> element, something like this:
<Resource name="jdbc/MySQLPool" auth="Container" type="javax.sql.DataSource"
factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory"
maxActive="100" maxIdle="30" maxWait="10000"
username="USERNAME" password="PASSWORD"
driverClassName="com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource"
url="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=Cp1251"
removeAbandoned="true" />
(I'm not sure if that's the correct driverClassName for MySQL, but your Resource should look somewhat like this).
For more info, try checking Tomcat's documentation on JNDI Resources and JDBC DataSources.

Typically context.xml and server.xml are separated, and you usually configure a data source on web-app level, that is in the context of that web app. The reason for that is that a data source connects not so much to a server but to a database within that server, and having multiple apps accessing the same database is not always a good idea (if you didn't design the apps for that).
That said, have a look at this tomcat wiki page which describes what you want (or what I think you want).
For authentication check out this thread on velocity reviews.