如何验证连接已释放

Question

I use the JDBC driver to connect to my database (made with a DBMS called SQLBase by the Centura Gupta company).

It is executed without problems (even I checked that the data is inserted into my database).

But then I execute a very simple SELECT statement and I get this error:

TypeError: Cannot read property 'createStatement' of undefined
    at /var/apis/api.test/connections/sqlbase.dposs1.js:86:25
    at JDBC.Pool.reserve (/var/apis/api.test/node_modules/jdbc/lib/pool.js:192:5)
    at Object.getCenturaQuery (/var/apis/api.test/connections/sqlbase.dposs1.js:79:15)
    at Object.verificarPagos (/var/apis/api.test/app/bancos/bancos.model.js:146:20)
    at getFacturas (/var/apis/api.test/app/bancos/bancos.rutas.js:7:18)
    at Layer.handle [as handle_request] (/var/apis/api.test/node_modules/express/lib/router/layer.js:95:5)
    at next (/var/apis/api.test/node_modules/express/lib/router/route.js:131:13)
    at Route.dispatch (/var/apis/api.test/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/var/apis/api.test/node_modules/express/lib/router/layer.js:95:5)
    at /var/apis/api.test/node_modules/express/lib/router/index.js:277:22

I am thinking that the release statement was not execute properly.

I use this code that I saw here: https://www.npmjs.com/package/jdbc

myConnection.release(connObj, function(err) {
    if (err) {
        console.log(err.message);
    }
});

After release I still have this JSON connection object (I think it should't exist anymore, but it still exists):

{
    "uuid": "30271a1a-db99-4ff2-8b6a-5befcbe8fbb4",
    "conn": {
        "_conn": {
            "warnings": null
        },
        "_txniso": [
            "TRANSACTION_NONE",
            "TRANSACTION_READ_UNCOMMITTED",
            "TRANSACTION_READ_COMMITTED",
            null,
            "TRANSACTION_REPEATABLE_READ",
            null,
            null,
            null,
            "TRANSACTION_SERIALIZABLE"
        ]
    },
    "keepalive": false
}

How can I check if the connection was released successfully before executing a SELECT satement?

I think the problem is around this JSON connection object.

Maybe it helps: I am developing with JavaScript and NodeJS on the server side.

Answer 1

I'm not a JavaScript person - but am a Gupta SQLBase person , and logic tells me that you can't run a 'Select' if you have released the handle ( connection ). Normally , from within Gupta's own toolset , you would perform in this order: 1) Connect a Handle 2) (Optionally) set the Isolation Level to either 'Release Locks' or 'Read Committed 1, 2 or 3' . 3) Run the Update using the same Handle 4) Run a Commit using the same Handle 5) Run a Select using the same Handle 6) (Optionally) Release the Handle ( or re-use it )

excuse if I have misunderstood the way JavaScript works - can only advise on the way Gupta works.