import groovy.sql.Sql

buildscript {
    repositories {
        mavenCentral()
    }

    dependencies {
        classpath 'com.microsoft.sqlserver:mssql-jdbc:6.4.0.jre8'
    }

    configurations.classpath.each { Sql.classLoader.addURL it.toURI().toURL() }
}

task somethingWithMSSQL() {
    def dbHost = "host"
    def dbPort = "1433"
    def dbUsername = "username"
    def dbPassword = "password"
    def dbName = "database"
    def dbDriver = "com.microsoft.sqlserver.jdbc.SQLServerDriver"

    def jdbcUrl = "jdbc:sqlserver://$dbHost:$dbPort;databaseName=$dbName"
    def sql = Sql.newInstance(jdbcUrl, dbUsername, dbPassword, dbDriver)

    // do something with MSSQL

    sql.close()
}