next.jdbc — com.github.seancorfield/next.jdbc 1.3.1086

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 (with an initial value) 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),
• execute-batch! -- given a PreparedStatement and groups of parameters, execute the statement in batch mode (via .executeBatch); given a connectable, a SQL string, and groups of parameters, create a new PreparedStatement from the SQL and execute it in batch mode.
• 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 Connection is created:

• :auto-commit -- either true or false,
• :read-only -- either true or false,
• :connection -- a hash map of camelCase properties to set, via reflection, on the Connection object after it is created.

The following options are supported wherever a Statement or 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,
• :timeout -- the query timeout,
• :statement -- a hash map of camelCase properties to set, via reflection, on the Statement or PreparedStatement object after it is created.

In addition, wherever a PreparedStatement is created, you may specify:

• :return-keys -- either true or a vector of key names to return.

active-tx? clj

(active-tx?)

(active-tx? con)

Returns true if next.jdbc has a currently active transaction in the current thread, else false.

With no arguments, tells you if any transaction is currently active.

With a Connection argument, tells you if a transaction is currently active on that specific connection.

Note: transactions are a convention of operations on a Connection so this predicate only reflects next.jdbc/transact and next.jdbc/with-transaction operations -- it does not reflect any other operations on a Connection, performed via JDBC interop directly.

execute! clj

(execute! stmt)

(execute! connectable sql-params)

(execute! connectable sql-params opts)

General SQL execution function.

Returns a fully-realized result set. When :multi-rs true is provided, will return multiple result sets, as a vector of result sets. Each result set is a vector of hash maps, by default, but can be controlled by the :builder-fn option.

Can be called on a PreparedStatement, a Connection, or something that can produce a Connection via a DataSource.

execute-batch! clj

(execute-batch! ps param-groups)

(execute-batch! ps param-groups opts)

(execute-batch! connectable sql param-groups opts)

Given a PreparedStatement and a vector containing parameter groups, i.e., a vector of vector of parameters, use .addBatch to add each group of parameters to the prepared statement (via set-parameters) and then call .executeBatch. A vector of update counts is returned.

An options hash map may also be provided, containing :batch-size which determines how to partition the parameter groups for submission to the database. If omitted, all groups will be submitted as a single command. If you expect the update counts to be larger than Integer/MAX_VALUE, you can specify :large true and .executeLargeBatch will be called instead.

Alternatively, given a connectable, a SQL string, a vector containing parameter groups, and an options hash map, create a new PreparedStatement (after possibly creating a new Connection), and execute the SQL with the specified parameter groups. That new PreparedStatement (and the new Connection, if created) will be closed automatically after use.

By default, returns a Clojure vector of update counts. Some databases allow batch statements to also return generated keys and you can attempt that if you ensure the PreparedStatement is created with :return-keys true and you also provide :return-generated-keys true in the options passed to execute-batch!. Some databases will only return one generated key per batch, some return all the generated keys, some will throw an exception. If that is supported, execute-batch! will return a vector of hash maps containing the generated keys as fully-realized, datafiable result sets, whose content is database-dependent.

May throw java.sql.BatchUpdateException if any part of the batch fails. You may be able to call .getUpdateCounts on that exception object to get more information about which parts succeeded and which failed.

For additional caveats and database-specific options you may need, see: https://cljdoc.org/d/com.github.seancorfield/next.jdbc/CURRENT/doc/getting-started/prepared-statements#caveats

Not all databases support batch execution.

execute-one! clj

(execute-one! stmt)

(execute-one! connectable sql-params)

(execute-one! connectable sql-params opts)

General SQL execution function that returns just the first row of a result. For any DDL or SQL statement that will return just an update count, this is the preferred function to use.

Can be called on a PreparedStatement, a Connection, or something that can produce a Connection via a DataSource.

Note: although this only returns the first row of a result set, it does not place any limit on the result of the SQL executed.

get-connection clj

(get-connection spec)

(get-connection spec opts)

(get-connection spec user password)

(get-connection spec user password opts)

Given some sort of specification of a database, return a new Connection.

In general, this should be used via with-open:

  (with-open [con (get-connection spec opts)]
    (run-some-ops con))

If you call get-connection on a DataSource, it just calls .getConnection and applies the :auto-commit and/or :read-only options, if provided.

If you call get-connection on anything else, it will call get-datasource first to try to get a DataSource, and then call get-connection on that.

If you want different per-connection username/password values, you can either put :user and :password into the opts hash map or pass them as positional arguments.

get-datasource clj

(get-datasource spec)

Given some sort of specification of a database, return a DataSource.

A specification can be a JDBC URL string (which is passed to the JDBC driver as-is), or a hash map.

For the hash map, there are two formats accepted:

In the first format, these keys are required:

• :dbtype -- a string indicating the type of the database
• :dbname -- a string indicating the name of the database to be used

The following optional keys are commonly used:

• :user -- the username to authenticate with
• :password -- the password to authenticate with
• :host -- the hostname or IP address of the database (default: 127.0.0.1); can be :none which means the host/port segment of the JDBC URL should be omitted entirely (for 'local' databases)
• :port -- the port for the database connection (the default is database- specific -- see below); can be :none which means the port segment of the JDBC URL should be omitted entirely
• :classname -- if you need to override the default for the :dbtype (or you want to use a database that next.jdbc does not know about!)

The following optional keys can be used to control how JDBC URLs are assembled. This may be needed for :dbtype values that next.jdbc does not recognize:

• :dbname-separator -- override the / or : that normally precedes the database name in the JDBC URL
• :host-prefix -- override the // that normally precedes the IP address or hostname in the JDBC URL
• :property-separator -- an optional string that can be used to override the separators used in jdbc-url for the properties (after the initial JDBC URL portion); by default ? and & are used to build JDBC URLs with properties; for SQL Server drivers (both MS and jTDS) :property-separator ";" is used

In the second format, this key is required:

• :jdbcUrl -- a JDBC URL string

Any additional options provided will be passed to the JDBC driver's .getConnection call as a java.util.Properties structure.

Database types supported (for :dbtype), and their defaults:

• derby -- org.apache.derby.jdbc.EmbeddedDriver -- also pass :create true if you want the database to be automatically created
• duckdb -- org.duckdb.DuckDBDriver -- embedded database
• h2 -- org.h2.Driver -- for an on-disk database
• h2:mem -- org.h2.Driver -- for an in-memory database
• hsqldb, hsql -- org.hsqldb.jdbcDriver
• jtds:sqlserver, jtds -- net.sourceforge.jtds.jdbc.Driver -- 1433
• mariadb -- org.mariadb.jdbc.Driver -- 3306
• mysql -- com.mysql.cj.jdbc.Driver, com.mysql.jdbc.Driver -- 3306
• oracle:oci -- oracle.jdbc.OracleDriver -- 1521
• oracle:thin, oracle -- oracle.jdbc.OracleDriver -- 1521
• oracle:sid -- oracle.jdbc.OracleDriver -- 1521 -- uses the legacy : separator for the database name but otherwise behaves like oracle:thin
• postgresql, postgres -- org.postgresql.Driver -- 5432
• pgsql -- com.impossibl.postgres.jdbc.PGDriver -- no default port
• redshift -- com.amazon.redshift.jdbc.Driver -- no default port
• sqlite -- org.sqlite.JDBC
• sqlserver, mssql -- com.microsoft.sqlserver.jdbc.SQLServerDriver -- 1433
• timesten:client -- com.timesten.jdbc.TimesTenClientDriver
• timesten:direct -- com.timesten.jdbc.TimesTenDriver
• xtdb -- xtdb.jdbc.Driver -- an XTDB wrapper around postgresql

For more details about :dbtype and :classname values, see: https://cljdoc.org/d/com.github.seancorfield/next.jdbc/CURRENT/api/next.jdbc.connection#dbtypes

on-connection clj macro

(on-connection [sym connectable] & body)

Given a connectable object, gets a connection and binds it to sym, then executes the body in that context.

This allows you to write generic, Connection-based code without needing to know the exact type of an incoming datasource:

  (on-connection [conn datasource]
    (let [metadata (.getMetadata conn)
          catalog  (.getCatalog conn)]
      ...))

If passed a Connection or a Connectable that wraps a Connection, then that Connection is used as-is.

Otherwise, creates a new Connection object from the connectable, executes the body, and automatically closes it for you.

on-connection+options clj macro

(on-connection+options [sym connectable] & body)

Given a connectable object, assumed to be wrapped with options, gets a connection, rewraps it with those options, and binds it to sym, then executes the body in that context.

This allows you to write generic, wrapped connectable code without needing to know the exact type of an incoming datasource:

  (on-connection+options [conn datasource]
    (execute! conn some-insert-sql)
    (execute! conn some-update-sql))

If passed a Connection then that Connection is used as-is.

If passed a Connectable that wraps a Connection, then that Connectable is used as-is.

Otherwise, creates a new Connection object from the connectable, wraps that with options, executes the body, and automatically closes the new Connection for you.

Note: the bound sym will be a wrapped connectable and not a plain Java object, so you cannot call JDBC methods directly on it like you can with on-connection.

plan clj

(plan stmt)

(plan connectable sql-params)

(plan connectable sql-params opts)

General SQL execution function (for working with result sets).

Returns a reducible that, when reduced (with an initial value), runs the SQL and yields the result. plan returns an IReduceInit object so you must provide an initial value when calling reduce on it.

The reducible is also foldable (in the clojure.core.reducers sense) but see the Tips & Tricks section of the documentation for some important caveats about that.

Can be called on a PreparedStatement, a Connection, or something that can produce a Connection via a DataSource.

Your reducing function can read columns by name (string or simple keyword) from each row of the underlying ResultSet without realizing the row as a Clojure hash map. select-keys can also be used without realizing the row. Operations that imply an actual Clojure data structure (such as assoc, dissoc, seq, keys, vals, etc) will realize the row into a hash map using the supplied :builder-fn (or as-maps by default).

If your reducing function needs to produce a hash map without calling a function that implicitly realizes the row, you can call:

(next.jdbc.result-set/datafiable-row row connectable opts)

passing in the current row (passed to the reducing function), a connectable, and an opts hash map. These can be the same values that you passed to plan (or they can be different, depending on how you want the row to be built, and how you want any subsequent lazy navigation to be handled).

prepare clj

(prepare connection sql-params)

(prepare connection sql-params opts)

Given a connection to a database, and a vector containing SQL and any parameters it needs, return a new PreparedStatement.

In general, this should be used via with-open:

  (with-open [stmt (prepare spec sql-params opts)]
    (run-some-ops stmt))

See the list of options above (in the namespace docstring) for what can be passed to prepare.

snake-kebab-opts clj

A hash map of options that will convert Clojure identifiers to snake_case SQL entities (:table-fn, :column-fn), and will convert SQL entities to qualified kebab-case Clojure identifiers (:builder-fn).

transact clj

(transact transactable f)

(transact transactable f opts)

Given a transactable object and a function (taking a Connection), execute the function over the connection in a transactional manner.

See with-transaction for supported options.

unqualified-snake-kebab-opts clj

A hash map of options that will convert Clojure identifiers to snake_case SQL entities (:table-fn, :column-fn), and will convert SQL entities to unqualified kebab-case Clojure identifiers (:builder-fn).

with-logging clj

(with-logging connectable sql-logger & [result-logger])

Given a connectable/transactable object and a sql/params logging function and an optional result logging function that should be used on all operations on that object, return a new wrapper object that can be used in its place.

The sql/params logging function will be called with two arguments:

• a symbol indicating which operation is being performed:
  • next.jdbc/plan, next.jdbc/execute-one!, next.jdbc/execute!, or next.jdbc/prepare
• the vector containing the SQL string and its parameters

Whatever the sql/params logging function returns will be passed as a state argument to the optional result logging function. This means you can use this mechanism to provide some timing information, since your sql/params logging function can return the current system time, and your result logging function can then calculate the elapsed time. There is an example of this in the Naive Logging with Timing section of Getting Started.

The result logging function, if provided, will be called with the same symbol passed to the sql/params logging function, the state returned by the sql/params logging function, and either the result of the execute! or execute-one! call or an exception if the call failed. The result logging function is not called for the plan or prepare call (since they do not produce result sets directly).

Bear in mind that get-datasource, get-connection, and with-transaction return plain Java objects, so if you call any of those on this wrapped object, you'll need to re-wrap the Java object with-logging again. See the Datasources, Connections & Transactions section of Getting Started for more details, and some examples of use with these functions.

with-options clj

(with-options connectable opts)

Given a connectable/transactable object and a set of (default) options that should be used on all operations on that object, return a new wrapper object that can be used in its place.

Bear in mind that get-datasource, get-connection, and with-transaction return plain Java objects, so if you call any of those on this wrapped object, you'll need to re-wrap the Java object with-options again. See the Datasources, Connections & Transactions section of Getting Started for more details, and some examples of use with these functions.

with-transaction+options exists to automatically rewrap a Connection with the options from a with-options wrapper.

with-transaction clj macro

(with-transaction [sym transactable opts] & body)

Given a transactable object, gets a connection and binds it to sym, then executes the body in that context, committing any changes if the body completes successfully, otherwise rolling back any changes made.

Like with-open, if with-transaction creates a new Connection object, it will automatically close it for you.

If you are working with default options via with-options, you might want to use with-transaction+options instead.

The options map supports:

• :isolation -- :none, :read-committed, :read-uncommitted, :repeatable-read, :serializable,
• :read-only -- true / false (true will make the Connection readonly),
• :rollback-only -- true / false (true will make the transaction rollback, even if it would otherwise succeed).

with-transaction+options clj macro

(with-transaction+options [sym transactable opts] & body)

Given a transactable object, assumed to be wrapped with options, gets a connection, rewraps it with those options, and binds it to sym, then executes the body in that context, committing any changes if the body completes successfully, otherwise rolling back any changes made.

Like with-open, if with-transaction+options creates a new Connection object, it will automatically close it for you.

Note: the bound sym will be a wrapped connectable and not a plain Java object, so you cannot call JDBC methods directly on it like you can with with-transaction.

The options map supports:

• :isolation -- :none, :read-committed, :read-uncommitted, :repeatable-read, :serializable,
• :read-only -- true / false (true will make the Connection readonly),
• :rollback-only -- true / false (true will make the transaction rollback, even if it would otherwise succeed).