The public API of the next generation java.jdbc library.

The basic building blocks are the `java.sql`/`javax.sql` classes:
* `DataSource` -- something to get connections from,
* `Connection` -- an active connection to the database,
* `PreparedStatement` -- SQL and parameters combined, from a connection,

and the following functions and a macro:
* `get-datasource` -- given a hash map describing a database or a JDBC
    connection string, construct a `javax.sql.DataSource` and return it,
* `get-connection` -- given a connectable, obtain a new `java.sql.Connection`
    from it and return that,
* `plan` -- given a connectable and SQL + parameters or a statement,
    return a reducible that, when reduced will execute the SQL and consume
    the `ResultSet` produced,
* `execute!` -- given a connectable and SQL + parameters or a statement,
    execute the SQL, consume the `ResultSet` produced, and return a vector
    of hash maps representing the rows (@1); this can be datafied to allow
    navigation of foreign keys into other tables (either by convention or
    via a schema definition),
* `execute-one!` -- given a connectable and SQL + parameters or a statement,
    execute the SQL, consume the first row of the `ResultSet` produced, and
    return a hash map representing that row; this can be datafied to allow
    navigation of foreign keys into other tables (either by convention or
    via a schema definition),
* `prepare` -- given a `Connection` and SQL + parameters, construct a new
    `PreparedStatement`; in general this should be used with `with-open`,
* `transact` -- the functional implementation of `with-transaction`,
* `with-transaction` -- execute a series of SQL operations within a transaction.

@1 result sets are built, by default, as vectors of hash maps, containing
    qualified keywords as column names, but the row builder and result set
    builder machinery is open and alternatives are provided to produce
    unqualified keywords as column names, and to produce a vector the
    column names followed by vectors of column values for each row, and
    lower-case variants of each.

The following options are supported wherever a `PreparedStatement` is created:
* `:concurrency` -- `:read-only`, `:updatable`,
* `:cursors` -- `:close`, `:hold`
* `:fetch-size` -- the fetch size value,
* `:max-rows` -- the maximum number of rows to return,
* `:result-type` -- `:forward-only`, `:scroll-insensitive`, `:scroll-sensitive`,
* `:return-keys` -- either `true` or a vector of key names to return,
* `:timeout` -- the query timeout.

Standard implementations of `get-datasource` and `get-connection`.

Also provides `dbtypes` as a map of all known database types, and
the `->pool` function for creating pooled datasource objects.

Optional namespace that extends `next.jdbc.prepare/SettableParameter`
to various date/time types so that they will all be treated as SQL
timestamps (which also supports date and time column types).

Some databases support a wide variety of date/time type conversions.
Other databases need a bit of help. You should only require this
namespace if you database does not support these conversions automatically.

* H2 and SQLite support conversion of Java Time (`Instant`, `LocalDate`,
  `LocalDateTime`) out of the box,
* Nearly all databases support conversion of `java.util.Date` out of
  the box -- except PostgreSQL apparently!

Types supported:
* `java.time.Instant`
* `java.time.LocalDate`
* `java.time.LocalDateTime`
* `java.util.Date` -- mainly for PostgreSQL

PostgreSQL does not seem able to convert `java.util.Date` to a SQL
timestamp by default (every other database can!) so you'll probably
need to require this namespace, even if you don't use Java Time.

Builders that treat NULL SQL values as 'optional' and omit the
corresponding keys from the Clojure hash maps for the rows.

Mostly an implementation namespace for how `PreparedStatement` objects are
created by the next generation java.jdbc library.

`set-parameters` is public and may be useful if you have a `PreparedStatement`
that you wish to reuse and (re)set the parameters on it.

`execute-batch!` provides a way to add batches of parameters to a
`PreparedStatement` and then execute it in batch mode (via `.executeBatch`).

Defines the `SettableParameter` protocol for converting Clojure values
to database-specific values.

This is the extensible core of the next generation java.jdbc library.

* `Sourceable` -- for producing `javax.sql.DataSource` objects,
* `Connectable` -- for producing new `java.sql.Connection` objects,
* `Executable` -- for executing SQL operations,
* `Preparable` -- for producing new `java.sql.PreparedStatement` objects,
* `Transactable` -- for executing SQL operations transactionally.

Provides functions for use with the `:table-fn` and `:column-fn` options
that define how SQL entities should be quoted in strings constructed
from Clojure data.

An implementation of `ResultSet` handling functions.

Defines the following protocols:
* `DatafiableRow` -- for turning a row into something datafiable
* `ReadableColumn` -- to read column values by label or index
* `RowBuilder` -- for materializing a row
* `ResultSetBuilder` -- for materializing a result set

A broad range of result set builder implementation functions are provided.

Also provides the default implemenations for `Executable` and
the default `datafy`/`nav` behavior for rows from a result set.

Specs for the core API of next.jdbc.

The functions from `next.jdbc`, `next.jdbc.sql`, and `next.jdbc.prepare`
have specs here.

Just `:args` are spec'd. These specs are intended to aid development
with `next.jdbc` by catching simple errors in calling the library.
The `connectable` argument is currently just `any?` but both
`get-datasource` and `get-connection` have stricter specs. If you
extend `Sourceable` or `Connectable`, those specs will likely be too strict.

In addition, there is an `instrument` function that provides a simple
way to instrument all of the `next.jdbc` functions, and `unstrument`
to undo that.

Some utility functions that make common operations easier by
providing some syntactic sugar over `execute!`/`execute-one!`.

This is intended to provide a minimal level of parity with
`clojure.java.jdbc` (`insert!`, `insert-multi!`, `query`, `find-by-keys`,
`get-by-id`, `update!`, and `delete!`).

For anything more complex, use a library like HoneySQL
https://github.com/jkk/honeysql to generate SQL + parameters.

The following options are supported:
* `:table-fn` -- specify a function used to convert table names (strings)
    to SQL entity names -- see the `next.jdbc.quoted` namespace for the
    most common quoting strategy functions,
* `:column-fn` -- specify a function used to convert column names (strings)
    to SQL entity names -- see the `next.jdbc.quoted` namespace for the
    most common quoting strategy functions.

In addition, `find-by-keys` supports `:order-by` to add an `ORDER BY`
clause to the generated SQL.

Some utility functions for building SQL strings.

These were originally private functions in `next.jdbc.sql` but
they may proof useful to developers who want to write their own
'SQL sugar' functions, such as a database-specific `upsert!` etc.