Creating a Table

Session.sql() API is exposed to execute raw SQL commands on the server. MySQL tables can be created using this API as shown below:

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        return session.sql('CREATE TABLE schemaName.tableName (column INT)')
            .execute()
            .then(() => {
                return session.getSchema('schemaName').getTable('tableName');
            });
    })
    .then(table => {
        // work with the Table object
    })
    .catch(err => {
        // something went wrong
    });

Listing all the existing tables

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        return Promise
            .all([
                session.sql('CREATE TABLE foo.bar (_id SERIAL)').execute(),
                session.sql('CREATE TABLE foo.baz (_id SERIAL)').execute()
            ])
            .then(() => session.getSchema('foo'));
    })
    .then(schema => {
        return schema.getTables();
    })
    .then(tables => {
        console.log(tables[0].getName()); // 'bar'
        console.log(tables[1].getName()); // 'baz'
    })

Dropping a Table

Dropping a testSchema.testTable with the Session.sql() API is similar to the above:

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        return session.sql('CREATE TABLE schemaName.tableName (column INT)')
            .execute()
            .then(() => {
                return session.sql('DROP TABLE testSchema.testTable')
                    .execute();
            });
    })
    .catch(err => {
        // something went wrong
    });

Handling data in existing tables

With a table testSchema.testTable such as the following:

+------+------+
| name | age  |
+------+------+
| foo  |   23 |
| bar  |   42 |
+------+------+

Table rows can be updated or deleted under some specific conditions, as shown below.

To update/delete specific rows from a table, one should provide the appropriate filtering condition when calling update() or by additionally calling the where() method. For more details about the expression format, please check the guide.

To update/delete all rows from a table, one should provide any expression that evaluates to true (if no expression is provided, executing the operation will result in an error) when calling delete() or by appending a call to where().

Deleting rows that match a given criteria

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        return table.delete()
            .where('name = "foo"')
            .execute()
            .then(() => {
                return table.select()
                    .execute();
            });
    })
    .then(result => {
        console.log(result.fetchAll()); // [ [ 'bar', 42 ] ]
    });

Deleting all rows

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        // The expression should evaluate to `true`.
        return table.delete()
            .where('true')
            .execute()
            .then(() => {
                return table.select()
                    .execute();
            });
    })
    .then(result => {
        console.log(result.fetchAll()); // []
    });

Updating rows that match a given criteria

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        // The criteria is defined through the expression.
        return table.update()
            .where('name = "bar"')
            .set('age', 50)
            .execute()
            .then(() => {
                return table.select()
                    .orderBy('name ASC')
                    .execute();
            });
    })
    .then(result => {
        console.log(result.fetchAll()); // [ [ 'foo', 23 ] [ 'bar', 50 ] ]
    });

Deleting all rows

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        // The expression should evaluate to `true`.
        return table.update().where('true').set('name', 'qux')
            .execute()
            .then(() => {
                return table.select().orderBy('age ASC').execute();
            });
    })
    .then(result => {
        console.log(result.fetchAll()); // [ [ 'qux', 23 ] [ 'qux', 50 ] ]
    });

Cursors

Similarly to the document-based API, iterating over result sets originating from regular relational tables can be done either with fetchAll() (as depicted up until now) and with the pull-based fetchOne() cursor or the push-based API using callbacks. The only difference in the later is the fact that any callback provided for handling column metadata will be ignored.

Pull-based approach

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        return table.select()
            .orderBy('age ASC')
            .execute();
    })
    .then(result => {
        console.log(result.fetchOne()); // [ 'qux', 23 ]
        console.log(result.fetchOne()); // [ 'qux', 50 ]
    });

Push-based approach

const mysqlx = require('@mysql/xdevapi');
const data = [];
const metadata = [];

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        return table.select()
            .orderBy('age ASC')
            .execute(row => data.push(row), meta => metadata.push(meta));
    })
    .then(() => {
        console.log(rows); // [['qux', 23], ['qux', 50]]
        console.log(metadata.map(column => column.getColumnName()); // ['name', 'age']
    });

Iterating over multiple result sets

const mysqlx = require('@mysql/xdevapi');

const procedure = `CREATE PROCEDURE proc() BEGIN
    SELECT name, age FROM testSchema.testTable;
    SELECT name, age from testSchema.testTable;
END`;

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        return session.sql(procedure)
            .execute()
            .then(() => {
                return session.sql(`CALL proc()`)
                    .execute()
            })
            .then(result => {
                let item = result.fetchAll();
                console.log(item); // [['qux', 23]]

                result.nextResult();

                item = result.fetchOne();
                console.log(item); // ['qux', 50]
            });
    });

Handling column metadata

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        const table = session.getSchema('testSchema').getTable('testTable');

        return table.select()
            .orderBy('age ASC')
            .execute();
    })
    .then(result => {
        const columns = result.getColumns();

        console.log(columns[0].getColumnName()); // 'name'
        console.log(columns[1].getColumnName()); // 'age'
    });

Retrieving the table size

The size of a given table can be retrieved using the count() method.

const mysqlx = require('@mysql/xdevapi');

mysqlx.getSession('mysqlx://localhost:33060')
    .then(session => {
        return session.getSchema('testSchema').getTable('testTable').count();
    })
    .then(count => {
        console.log(count); // 2
    });

Column Types

It is important to understand how MySQL column types are translated to JavaScript/Node.js native types. One case worth a special mention is the fact that, by default, every possible number higher than 2^53 - 1 (the maximum safest integer in JavaScript) or lower than -2^53 + 1 (the minimum safest integer in JavaScript) will be preserved as a string in order to avoid loosing precision. However, an application can customize this behaviour by selecting from one of the following alternatives instead:

• all integers are preseved as a string
• all integers are preserved as a BigInt
• only unsafe integers are preserved as a BigInt

Selecting the appropriate strategy for handling unsafe integers in a result set can be done via a corresponding connection option.

Convert all integers in the result set to a JavaScript string

mysqlx.getSession({ integerType: mysqlx.IntegerType.STRING, host: 'localhost', user: 'root' })
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // ['1', '18446744073709551615']
    });

mysqlx.getSession('mysqlx://root@localhost?integer-type=string')
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // ['1', '18446744073709551615']
    });

Convert only unsafe integers in the result set to a JavaScript string (DEFAULT)

mysqlx.getSession({ integerType: mysqlx.IntegerType.UNSAFE_STRING, host: 'localhost', user: 'root' })
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1, '18446744073709551615']
    });

mysqlx.getSession('mysqlx://root@localhost?integer-type=unsafe_string')
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1, '18446744073709551615']
    });

Convert all integers in the result set to a JavaScript BigInt

mysqlx.getSession({ integerType: mysqlx.IntegerType.BIGINT, host: 'localhost', user: 'root' })
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1n, 18446744073709551615n]
    });

mysqlx.getSession('mysqlx://root@localhost?integer-type=bigint')
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1n, 18446744073709551615n]
    });

Convert only unsafe integers in the result set to a JavaScript BigInt

mysqlx.getSession({ integerType: mysqlx.IntegerType.UNSAFE_BIGINT, host: 'localhost', user: 'root' })
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1n, 18446744073709551615n]
    });

mysqlx.getSession('mysqlx://root@localhost?integer-type=unsafe_bigint')
    .then(session => {
        return session.sql(`SELECT 1, 18446744073709551615`)
            .execute();
    })
    .then(res => {
        console.log(res.fetchOne()); // [1, 18446744073709551615n]
    });

Statements created and executed by an application that operate with BIGINT, DECIMAL or NUMERIC can also be specified with a JavaScript string or BigInt (if it is an integer). This is possible on every method and API used as a CRUD statement building block, and additionally, on SQL placeholder assignments, like in the following examples.

Assuming a table t within an existing schema s created with:

CREATE TABLE s.t (unsafeNegative BIGINT, unsafePositive BIGINT UNSIGNED);

Insert an unsafe integer in a BIGINT column

mysqlx.getSession({ user: 'root', host: 'localhost', schema: 's' })
    .then(session => {
        return session.getDefaultSchema().getTable('t')
            .insert('unsafeNegative')
            .values(-9223372036854775808n) // BigInt('-9223372036854775808') or '-9223372036854775808'
            .execute();
    });

mysqlx.getSession({ user: 'root', host: 'localhost', schema: 's' })
    .then(session => {
        return session.sql(`INSERT INTO s.t (unsafeNegative, unsafePositive) VALUES (?, ?)`)
            .bind('unsafePositive', 18446744073709551615n) // BigInt('18446744073709551615') or '18446744073709551615'
            .execute();
    });

Update an unsafe integer in one or more records with a BIGINT column

mysqlx.getSession({ user: 'root', host: 'localhost', schema: 's' })
    .then(session => {
        return session.getDefaultSchema().getTable('t')
            .update()
            .where('true')
            .set('unsafePositive', 18446744073709551615n) // BigInt('18446744073709551615') or '18446744073709551615'
            .execute();
    });

The following table depicts a non-comprehensive and possible mapping between data types.

Additionally, except for JSON fields, one must also account for the following:

• Boolean values (true and false) will be coerced into any kind of numeric type
• null or undefined will be coerced into the MySQL NULL value

Types as column metadata

One of the dimensions provided as part of the column metadata is its type. However, most of the times this type is not a direct match of the SQL data type. This happens not only because MySQL itself extends the set of types defined by the SQL standard but also because not all queries happen over a table with a defined schema. For instance:

session.select('SELECT 1 + 2.0')
    .execute()
    .then(res => {
        const columns = res.getColumns();

        console.log(columns[0].getType()); // 'DECIMAL'
    });

This query results in one of the values being coerced and the protocol will encode the result set field using the coerced type as inferred by the server. The list of field types is somewhat limited but the protocol encodes additional metadata that allows to extract more details about each column type. The following table depicts the mapping between SQL data types, X Protocol field types and X DevAPI column types.

In a nutshell, every other type not listed maps, in X DevAPI, to STRING in case the column charset is not binary, otherwise it maps to BYTES.