dataBasically

a relational database management system that includes B+ tree indices, efficient join algorithms, query optimization, multigranularity locking to support concurrent execution of transactions, and database recovery

Usage of Database

The Database class represents the entire database. It is the public interface of our database - we do not parse SQL statements in our database, and instead, users of our database use it like a Java library.

All work is done in transactions, so to use the database, a user would start a transaction with Database#beginTransaction, then call some of Transaction's numerous methods to perform selects, inserts, and updates.

For example:

Database db = new Database("database-dir");

try (Transaction t1 = db.beginTransaction()) {
    Schema s = new Schema(
        Arrays.asList("id", "firstName", "lastName"),
        Arrays.asList(Type.intType(), Type.stringType(10), Type.stringType(10))
    );
    t1.createTable(s, "table1");
    t1.insert("table1", Arrays.asList(
        new IntDataBox(1),
        new StringDataBox("John", 10),
        new StringDataBox("Doe", 10)
    ));
    t1.insert("table1", Arrays.asList(
        new IntDataBox(2),
        new StringDataBox("Jane", 10),
        new StringDataBox("Doe", 10)
    ));
    t1.commit();
}

try (Transaction t2 = db.beginTransaction()) {
    // .query("table1") is how you run "SELECT * FROM table1"
    Iterator<Record> iter = t2.query("table1").execute();

    System.out.println(iter.next()); // prints [1, John, Doe]
    System.out.println(iter.next()); // prints [2, Jane, Doe]

    t2.commit();
}

db.close();

More complex queries can be found in src/test/java/edu/berkeley/cs186/database/TestDatabase.java.